Soloists that could've been viral and didn't

I feel like soloists have by far the lowest success rate in kpop, even idols like Daniel who had all the star power can't find a way to stay on top. Who do you think had all the talent and resources to become the next big soloist but didn't for some reason? I always wished that Luna from f(x) had been more successful. I still listen to Free Somebody the entire mini album is so strong.