The snap was always the dumbest part of the entire avenger series. Let's say for example, you have a bunch of deer that are eating the forest bare, so you let hunters kill half of them... Then what happens next? You have the exact same problem in a few years. The snap solves nothing.
Also if you can snap your fingers and do this, why can't you snap your fingers and make twice the food supply?
The snap is just stupid, even in a world made-up physics-defying superheroes.
To be fair, it made slightly more sense in the comics, though still batshit. In the comics there was no noble purpose like they tried to shoehorn in for the MCU. IIRC, Thanos was literally doing it to impressed Death (the cosmic entity) to gain her affection.
It's stupid only because they try to rationalize it.
Comics Thanos just wants to commit genocide so his crush notices him. That's also stupid, but he's a big purple space alien so what can you expect? Using a magic space glove powered by stardust and wishfish to kill half of all life as an incredible gesture of his devotion to Death makes internal sense.
Even worse than that. 50% of all life dies, right? That's 50% of the plants too. If you know anything about food chains, taking 50% of everything leaves the top of the chain massively overloaded.