Thanos was not right at all.

Well if his plan was to stop every celestial emergence, in a way, yes. But the eternals found a new way to stop that. So he was wrong when it comes to murdering trillions and trillions.

Well, if someone feels himself agrees with Thanos very much, he can do others a great deal of favor by saving resources on himself. (I mean like diet, live in nature)

He helped in Eternals so I really don't know. I don't think he was right, just that he may have done something helpful.

Well, in the comics Thanos is nothing but a simp