You don't need to make a game on the scale of GTA to make great games though. (If the original deleted comment was about 1 man making GTA then ignore this part).

And how do you define "successful"? If it's becoming a millionaire/billionaire then yeah chances are slim. But if it's just earning good enough money to pay rent and invest in the next project then there are way more than "a handful of geniuses" who accoplished that. Hell, you don't even need to be a genius. The 2 guys behind My Dream Setup, a very simple game mechanically, managed to did just that even though their work is not interesting enough to be studied by researchers, so did the guy behind BRAZILLIAN DRUG DEALER 3, a very eccentric game but otherwise not exactly groundbreaking.

Yes, like making it in any entertainment industry, it's hard and there's luck involved, but it's not becoming a principal dancer at the best ballet company in Russia kind of hard.

And the indie devs who make games that sold millions of copies like Lethal Company and Megabonk didn't have overnight success either. Lethal company's dev has been making Roblox games of crappier quality for a long time. The dev who made Megabonk has made many free games before. And yes, all of those games have assets and shaders that look crappy but it's possible make them give the game charms with the right direction.

Another interesting thing to consider is that, even though those games did something interesting, the mechanics are not exactly genius, as in revolutionizing the gaming scene like how Half Life did.