G2A doesn't suck because it's not trustworthy, it sucks because it takes money away from hard working devs.
uh
except for the uncommon cases of people selling keys from giveaways and the even rarer cases of stolen keys, someone has to buy the games in the first place to sell them.
it's no different from buying a pre-owned game from gamestop or another store. the devs don't make money off of pre-owned games, the store does.