Mister
Ignorance can be remedied. Stupidity is incurable.
Well maybe the perception of reality is the wrong way to phrase it, but his reality warping is heavily nerfed compared to what you see in the comics. In every case of him using the Reality Stone, the effects went back to normal as soon as he left. Even with the other stones helping out, there is nothing that says that the effects would be permanent in the way you'd need to create resources out of nothing.
The answer could also be that, in those occasions, Thanos simply chose not to make the changes permanent. He's Thanos. He does isht like that.
You've taken an assumption on the limits of the reality stone and are running with it like a stated fact.