Having too much responsibility to early in one's career I think is a significant risk factor, especially combined with certain personality types. Moreso if you lack a strong professional network and/or mentorship. This situation is often correlated with clueless and/or ineffective and/or hostile management, which is it self an exacerbating factor.
I don't think it's the only cause, but it's probably a common one.
Building and shipping great software that goes on to have few or no users? Burnout.
Building widely used software but you come to believe it does more harm than good? Also burnout.
Avoiding it requires believing in the value of the things you have done; imo overwork can only speed up the process, but will not cause it if you believe in the rightness of what you are doing.
You find yourself thinking “I was sure that would be good and worked hard, and it turned out not to be. Now I am sure my new project will be good, but how can I know it’s going to go differently”.