Yours is not a "more obvious and powerful truth". In fact, it already assumes the first of my viewpoints, that people who do better things are going to be more successful. If you are powerless to effect your own future, then your motive to act is irrelevant.
I'm not saying that the first viewpoint is wrong, but I'm not saying it's right either. I would like to point out that:
(a) it is a viewpoint that you're being sold, force fed all the time, by various people
(b) It is a viewpoint that will be stronger among the wealthy and powerful
(c) It's a viewpoint that benefits the wealthy and powerful to convince us all of, because it tells us that they're wealthy and powerful because they deserve it
(d) The "power of positive thinking" is likely to be a successful meme, since people are more likely to spread that idea than the alternative. That is, if you think you can change things with thinking, then you're likely to keep thinking it and spread the thought to other people. If you don't believe that, then there's no motivation to spread your ideas to others.
(e) The success of a meme is not necessarily an indicator of its truth
If you want to know what I think, it's that the "truth" is significantly more complicated than either of these viewpoints would indicate. The degree of control we have over our own futures is very unclear, and probably extremely variable. Some of us probably have much more control than others, but it depends on what you consider to be "control".