Fair enough. Let's imagine for a moment that some "smart" people don't maximise income. My question then is: why don't they use those extra 40 hours to optimise whatever makes them tick (solving global problems, building their own biz, creating great open source software) instead of being paid truck driver rates making somebody else rich? That still doesn't seem very smart.

I just left a low paying 80 hour a week job for a high paying 40 hour a week job with that exact logic - I can do what makes me tick in my spare time.

As it turns out, that's a lot harder than you're making it sound. I absolutely loved my previous job, where I was building a quality product that I knew my customers would enjoy. There were some leadership-related issues that came up there, so I thought I could build a product on my own in my extra 40 hours a week. Now I have no product (or product ideas) and no customers. Instead I spend my time networking with people who might have those two things. I feel like I lost out, even though I'm getting higher pay.