I know people who quit and were glad that they did so. I know people who graduated, but with the realization that research wasn't for them, and they pivoted into something else. But I honestly can't think of anyone who stuck through it and was worse off afterwards.
So you're saying you've heard of people who quit and were successful and you've heard of ones who graduated and pivoted and were successful, but not ones who graduated and weren't successful. It's almost like when you hear of someone it's more likely because they were successful in some way and the unsuccessful ones you hear less often.