Probably for so many reasons, the substances can numb and take away bad thoughts and feelings caused by, in part, by their povity.
It's an instant gratification, and instant fix, which is why they want more of it. But eventually the substance, the fix, eventually it wares out until the next one.
( G/PP 💩💩💩💩💩&#128, Mon 13 Jun 2011, 18:10, archived)