It is true that the available banking for marijuana business is unstable, most of it provided by state-chartered banks and credit unions that do not have the federal government as their primary regulator. It is also true that marijuana-related banking is expensive — $5,500 a month for a checking account at one bank in Massachusetts, according to The Boston Globe.

But reform could make matters worse. Big investment banks and corporations want a more streamlined banking regime in order to scale up marijuana operations. Many members of Congress have rallied behind the SAFE Banking Act not because their voters care about pot but because their donors care about money. The old hippie who grows a couple of plants in his backyard in Santa Cruz is not the guy who is paying the former House speaker John Boehner to lobby on behalf of the National Cannabis Roundtable.

Relatively well-capitalized pot businesses are already turning into big corporations. Last year Bank of America and Goldman Sachs reportedly advised Constellation Brands on a $4 billion investment in Canopy Growth, a “multifaceted cannabis company” headquartered in Ontario. (Marijuana is legal nationally in Canada.) On Tuesday the retired New England Patriots tight end Rob Gronkowski revealed his new role as a spokesman for Abacus, a corporation that sells cannabis-derived health products.

Any businessman would want in on marijuana. It is a legal drug, and a legal drug is a gold mine. If it is addictive, it creates a compulsion to purchase. As we learned from the tobacco hearings of the 1990s, not all businessmen can resist exploiting their customers’ compulsions. The National Institute on Drug Abuse says marijuana “can” be addictive. But even if a drug is merely “habit forming,” as many doctors believe marijuana to be, it creates an unlevel playing field between seller and consumer. The more “efficient” the market, the more powerful this inequality.

Whether or not marijuana’s Schedule 1 classification makes sense medically, it serves a purpose politically. Often government intervention requires thwarting businessmen’s antisocial impulses, not just unleashing their productive ones. Politicians are reluctant to admit to being “anti-business.” So a lot of useful regulation gets carried out under pretexts.