If American Idol gets alot of views cuz of theirsingers, howcome most of the singers aint succesful after AI?

Theres so much hype about all these singers cuz ppl say their album sales will skyrocket, but i dont see that happening to too many of those idols. Kelly clarkson is the only idol that has even came close to that. after kelly clarkson there was carrie underwood, and thats about it. where's all the talent at? just cuz they have a good voice dont mean that they could make good songs, like come on!