as most of everything was metioned before why i do, here's another main reason:

i get bad anxiety and tend to get really stressed over stupid shit, so smoking can relax me and i can think better while high. plus, if you have nothing to do why not? most people can still focus and maintain, and in your head it just makes everything not as boring as it might be... so in other words it just makes the day more fun, and that's all that needs to be said.