Some drugs (alcohol, opiates, meth) do fuck up your brain with long term consistent use associated with addiction, but most people don’t fall into that unless they have some sort of severe external stress or genetic predisposition. You can see this with alcohol which despite its acceptance by society is one of the most harmful drugs out there, but most people who consume it do so in relative moderation.

Drug prohibition fucks ups society way more than drugs can fuck up your brain. It creates a police state that targets the poor and minorities. It gives money to cartels and gangs that cause violence. It doesn’t even stop drug use, those who want it can still get it, it just makes drugs less safe as theirs no quality control leading to adulterants and an incentive to make overly concentrated substances like fentanyl, which probably wouldn’t exist without prohibition.

What people put in their body is none of your fucking business