[eslaught]

Your analysis seems to assume that the only form of motivation is external. By this logic, persistent/obstinant people do things because they hope for some external reward (e.g., praise, recognition, fame, possibly financial compensation). The difference is merely at the granularity of the goal this is attached to.

My experience is that the persistent people I know have at least some degree (and often a large degree) of internal motivation. They do things because the process of problem solving is rewarding in and of itself, and/or they have some intrinsic motivation about solving the problem. They are not out to please anyone else except themselves.

Maybe no one is purely 100% internally motivated. But my experience is that the more persistent people I know generally have a higher percentage of internal motivation. In contrast the people who give up more easily generally have a lower percentage of internal motivation; if they really only care about the external reward, it often turns out there are lots of ways to do that, and many are shorter than solving "hard" problems.

[ensocode]

Thanks, I thought the same but as you mentioned, there is no 100% intrinsic/extrinsic motivation. On the other hand there could be some self esteem problem within oneself which triggers motivation intrinsically but has external sources (i.e. childhood, always not enough, no unconditional love) so in the end there might not be a difference between internal and external.

[munificent]

I think the line between extrinsic and intrinsic motivation is very blurry.

If you're doing something because you want some recognition or fame, that's arguably extrinsic: you're doing the thing because you want other people out in the world to pat you on the back. But while you're doing the work, you're mostly thinking about how good it will feel to get that pat on the back. At that point, is it really that different from other instrinsic motivations?