President Donald Trump made a grave mistake in softening the federal stance on marijuana by reclassifying it as a Schedule III drug. The dangers of weed are real, insidious and growing worse.

At Trump’s direction, Acting Attorney General Todd Blanche on Thursday rescheduled it, removing it from the category of drugs like heroin to one for strong medicines.

Decades of propaganda seem to have convinced tens of millions of Americans that marijuana is benign, a harmless substance less worrisome than booze, cigarettes or even soda.

Increasingly legal and available around the country, pot is marketed to kids — through wacky colors, flavors and names — in a way that would horrify parents if done by gambling or porn companies.

Yet the drug has a profound impact on brain development in children, adolescents and young adults. Study after study has documented its profoundly destructive effects.

A major 2025 neuroimaging study published in the JAMA Network, for example, found that marijuana makes users less productive and attentive.

The drug disrupts cognitive functioning and brain activation concerning “working memory,” which controls how we follow instructions, solve problems and hold information, and its negative impact among regular users is long lasting.

People with serious mental illness use pot to self-medicate, but the drug can induce schizophrenic reactions.

For younger users, marijuana use is associated with a significant boost in the development of major psychiatric disorders.

The popular representation of a stoner is a goofy, mellow individual who at worst scarfs down too many cookies.

But younger, chronic marijuana users are way more likely to act out violently, kill other people and commit suicide than their non-user peers, even ones with major mood disorders.

None of this is surprising. Marijuana inhibits the cognitive processing that lets people think through the consequences of their actions.

Trump’s reclassification of marijuana as a Schedule III drug isn’t the same thing as national legalization.

But it will make it easier for pot companies — increasingly major corporations — to get bank loans, accept credit cards and deduct marketing expenses from their business taxes.

That means more aggressive advertising and greater availability of the drug.

Perhaps worst of all, the move helps remove the stigma of using a substance that most people have associate with unproductive, anti-social types.

Instead of giving his stamp of approval to the drug, Trump ought to use the power of his office to find ways to curb its use.

He should push for tougher federal restrictions, and use his vast reach to counsel young people against smoking.

The president is famous for counseling his children to follow his example and avoid alcohol and drugs.

The children of America deserve the same lesson.