Well, you aren’t firing fast enough. Hire them and fire them like water and eventually good ones will be forged from their failures.
They have been artificially exempted from failure, and without it none of them will grow into anything useful. With it some eventually will.
Millennials were kept out of the kitchen because they could get burned. Gen X was warned not to touch the oven because they could get burned. Baby boomers were allowed to touch the oven and get burned.