I think it is partly that it is less so frowned upon (MN isn't a valid snapshot of reality!) than it used to be. And other drugs are more commonplace now given the price of alcohol and the more commonplace they get, the more open people are about them.
All this 'WeEd SmOkeerz R loZers' sort of talk is why a lot of people who are nothing at all like that, are not open about it.
I smoke weed every now and again.
It's one of the very few ways I can guarantee I will get more than 3 hours sleep (insomniac from a very young age).
I do not have MH issues beyond being a bit of an introvert.
I own 6 houses.
I have two degrees (postgrad).
I am a vegan (for the 'Don't care about anything but themselves' brigade) and also work in MH in a career formed entirely from a desire to help those less fortunate than me.
I am not saying I am amazingly successful, (I am probably the equivalent of scum in MN world where everyone lives in a penthouse in London and earns 6 figures) but I am hardly a loser.
I like the feeling of it, it helps me wind down, laugh, feel pleasure after a hard day where I haven't been able to let go or stop thinking about serious things. I am in my own home, harming nobody but myself other than the actual smoking part of it, I really do not think it does me any harm at all and as I generally do not smoke at all other than this, I think that part is negligible.