Good point, but wrong conclusion. Yeah, me selling crack wouldn’t change anything on a world wide scale, but it would change things for the worse inside my sphere of influence. The only thing person can have a little and albeit a very limited effect on.

So person shouldn’t sell crack out of simple selfish desire to not feel bad(guilt/cleaner conscious), the crackhead will likely just go to another dealer, not in the vain hope of having any actual effect on the wider world