system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: Are there any negative consequences to smoking pot, if not, why has it been illegal for so long?
gpt
In teenagers, pot has been shown to slightly decrease test scores and IQ later in life, though whether there are confounding variables in any test like this is, of course, unknowable. Once the brain is fully developed, though, I've never heard of any significant downsides. It remains illegal in large part due to lobbying by tobacco, alcohol, pharmaceutical, and prison corporations who all want to keep competition off the market (and increase their own business in the case of prisons), and also due to social conservatives who just want to keep everything the same regardless of if it makes sense.