You have to be stubborn enough to succeed in a world where the majority of people will tell you you're going to fail, you have to ignore all that.
Often times however, you do fail.
Almost anything worth doing is difficult and to an extent risky. You are likely to fail both wasting time, money and other resources. But you are also likely to win big.
Anything that is easy is either already solved, or leads to mediocrity or pays too less.
To succeed at your goal you either need to get lucky or simply persist until you get there. Some can, many can't. Some just get lucky.