His Wikipedia article is rather vague on how he made his wealth,

He is or has been a director of a lot of companies; you can find a substantial background on his directorships over here. Given the salaries that high-end directors tend to receive, it;s no wonder he's built up that sort of wealth.

So is being one of the worst presidents in US history something to be proud of?

I'll admit, my knowledge of US history is very poor, as I do not live there. All I really know about Obama is that he seems to be a substantial improvement on Bush; I have absolutely no basis for comparison with anyone further back than that.

But becoming US President is, I think, something to be proud of in and of itself. It can't be something that's easy to do.