Not really, I mean if you made a profit out of it so why not? Ordinary people might think you are insane because they've only bought GPU for gaming and not for making money, but you are making money that could be called as a productive act.
I think people are offloading their ethereum mining gear before they go pos. Mining gear will flood the market around that time so you'll have trouble selling them afterwards
Like you could only mine eth

That Ethereum is switching to POS has been said already back in 2017.

I'll only believe that when it happens.
POS simply has a few crucial disadvantages, like 'Nothing at stake' etc.
@OP
Very good buy! Have fun mining!
Agree with that, there's plenty of worthy altcoins other than ETH so there's nothing to worry about.