I started my senior year of high school a few weeks after Woodstock wrapped up.

No, I didn't actually attend the legendary 1969 music festival. (Or, if I did, I don't remember it.)

I date myself this way merely to give some sense of the times and the cultural landscape — all tangerine trees and marmalade skies — in which, way back when, I indulged my share of what are pleasingly called youthful indiscretions.

To be frank, I may have indulged a couple of shares. So trust me when I say that I intend no moralizing in regard to today's burning public policy topic:

Pot, grass, weed, marijuana.

The momentum for full legalization of America's most popular illegal drug seems irresistible, around the nation and here in Minnesota. Maybe the clearest indicator was that the issue of recreational pot did not become any kind of a plaything during last year's election campaign, even though DFLers far and wide came out for it, including nearly all of the party's main gubernatorial candidates and the eventual winner, newly installed Gov. Tim Walz.

In recent years, no less a liberal than newly retired Gov. Mark Dayton had only grudgingly accepted approving limited medical use of cannabis. Yet Republicans took no outspoken stand against the DFL's rather sudden transformation into a pot party.

It may be that Minnesota conservatives, after their 2012 debacle pushing a failed same-sex marriage constitutional ban, have learned that social issues can be politically treacherous once attitudes start changing — and they see the times a-changing that way on marijuana.

It's hard to miss. Although voters in neighboring North Dakota rejected a full-legalization referendum question in the November election, Michigan became the first Midwestern state — and the 10th state in America — to take the leap, while decidedly levelheaded Missouri and Utah joined more than 30 other states in approving some medical use of the drug.

In Minnesota, not one but two new political parties proudly named for their single issue of choice — the Grassroots-Legalize Cannabis Party and the Legal Marijuana Now Party — drew enough votes in statewide races to achieve "major party" status.

All told, about one-quarter of all Americans live today in places where marijuana is fully legal, and a good-sized majority live where it's at least medically available.

Minnesota isn't likely to resist inhaling this intoxicating trend indefinitely.

And yet, as we face that reality, there is a truth about the nature of all addictive, habit-forming commodities that ought to be squarely confronted by a state contemplating easing and expanding access to another of them — and thinking about how to structure, regulate and manage that new "industry."

It's the truth that from alcohol to tobacco to gambling to pornography to the most powerful narcotics — and including marijuana — habit-forming products are consumed in wildly disproportionate quantities by their heaviest users.

This means that the alluring profits and tax revenue promised by these kinds of goods always will be extracted mainly from their most compulsive buyers, the ones most likely to be harming themselves.

How harmful pot is overall remains a subject of study and dispute — with the need for more and better research being one point of widespread agreement. A large-scale review of research two years ago by the National Academies of Sciences, Engineering and Medicine found a range of possible health and behavioral harms, particularly of a "psychosocial" kind (think mental lethargy) and particularly among heavy users and the young. There is mixed evidence of increased use and associated problems (impaired driving, etc.) overall in states that have legalized pot.

Still, it's probably fair to say that research so far generally supports the longstanding argument of marijuana's defenders that, as intoxicants go (compared not least to booze), weed is comparatively safe for the occasional social dabbler.

Meanwhile, two main benefits are legitimately claimed by proponents of legalization (beyond the greater convenience and enjoyment of pot users). First, many thousands of nonviolent marijuana users, disproportionately minority, may escape incarceration and/or a criminal record that can blight lives more severely than using marijuana moderately ever would — while criminal organizations would be denied the oversized profits that flow from pot prohibition

Second, of course, government can in effect capture some of those profits in tax and licensing revenue — reportedly running about $300 million a year in Colorado.

And that should bring us back to the question of where those handsome revenues would come from, along with the profits that would be earned by a legal recreational cannabis industry.

The degree of concentration in the consumption of habit-forming commodities is often surprising. Many activities and consumer goods show considerable concentration. (The most avid gardeners buy far more than their share of gardening supplies and gear.) But use of addictive products is still more profoundly lopsided.

Research shows that 10 percent of drinkers consume more than half of all the alcohol sold, while 10 percent of gamblers may bet more than two-thirds of the money wagered. And of course the latest statistics tell us that just 14 percent of U.S. adults now smoke 100 percent of the cigarettes.

Marijuana use shows the same pattern, with or without legalization. A 2014 White House study reported that fewer than 20 percent of near-daily marijuana smokers accounted for about 80 percent of the money spent on pot, a concentration level as high as any other illicit drug they studied.

One Colorado study conducted since legalization, and cited in an extensive Vox report on legalization, shows that the heaviest 22 percent of users, who essentially use every day, consume two-thirds of all the marijuana sold. Fewer than 30 percent of total users consume almost 90 percent.

So make no mistake. While most marijuana users — like most drinkers and most gamblers — use their "drug of choice" occasionally, moderately and enjoyably, the industries that market such goods (and the revenue government draws from them) depend heavily on a small number of chronic users who may well be having grave difficulties.

It's a sobering fact that Minnesota should ponder as it considers cutting itself in on the pot action. A frequent and reasonable response, to be sure, one Walz has been quoted invoking, is that "prohibition doesn't work."

It certainly never has kept many pathological gamblers, slavish drinkers, habitual stoners and so on away from the elixirs they crave and will go to great trouble to find.

But just because we can't solve a problem — that doesn't mean we couldn't make it worse.

If legalization is coming, let's take time to think about how Minnesota can avoid merely luring more of the vulnerable into a dependency, and instead use the state's new resources effectively to help those already there.

D.J. Tice is at Doug.Tice@startribune.com.