That depends on how good the concept is! Plenty of indie games have succeeded without gambling mechanics, look at something like Baba Is You for instance. I don’t know that the developer became rich off of it but be seems to have done well enough.
This only works if you either already have a brand like Zachatronics or if you have the patience to support/polish these small games for years till the random slot machine of the universe drops you enough reviews that you get critical mass and decent sales… or you pay for PR and you can successfully profit from even a shit game with enough PR money so why bother at that point…
Your right about a good concept winning a lot of good will and making success possible with less polish, but these days it doesn’t subtract the “risk of never being discovered” if you make an iOS app your just one of millions in the App Store if it’s on steam the shovelware isn’t as bad and discovery is better but it still requires market understanding in order to stand out.
The reason I referenced Baba Is You is because that concept was so incredibly brilliant, I legitimately believe you could have dropped the game into five parallel universes and it would have gotten attention every single time. Just get the game in front of one journalist for five minutes, and they'll very quickly see how brilliant it is.
Discovering a game concept like that is hard, but it does happen.
