After sex you feel like smoking a cigarette. After school you feel like smoking something a whole lot stronger. You only get disciplined during sex if you want to. Drinking drives people to sex, whereas school drives people to drink. After sex you feel like you have accomplished something.
Sex is cheaper.
Even if you have to pay for a hooker, it is still cheaper than paying thousands of dollars in tuition. At least you have a choice whether or not you want to have sex.