I wonder if he might not have felt the same way because he put in so much less effort, but still did well. If you put in a lot of effort regardless of the outcome you can think back that you tried your best. If you half-ass it and things go well, then you might feel that you don't deserve it, but if things don't go well, then you feel bad for not trying.

Being able to work hard is a talent itself. In many cases it's the most important one.