The point is that you can only do something for so long before you need to switch it up. And once you've made your money, you aren't motivated by that any more.
That might be true, and I'm not reading into Mansfield's motives, nor did I assume you were. What I took issue with was your statement that the "dream in business is to get rich." I think that's a modern American dream furthered by certain business schools. Of course every business wants to make money, and make a good profit. But our modern business culture that chases the dollar and lets quarterly profits dictate business strategy is poison in the well of American capitalism.
Old school tech companies used to invest heavily in R&D. Their focus was making innovative products. Look back 50 years, and Xerox, Bell Labs, and Hewlett-Packard were changing the face of technology. Apple grew out of that culture, while it still existed, and fortunately still maintains it. But they are one of the last of a dying breed. Everything is about ROI now -- no research, just copy what everyone else is doing and churn out cheap ****. This is not just hardware, either -- this attitude is rampant in software. Facebook, Instagram, Zynga. These companies are focused on getting as rich as possible. Not on serving customers in the best way. Although business schools and venture capitalists really infected the tech industry, this started with Microsoft, and Bill Gates. A guy who retired early and rich beyond imagination. I don't say that to make a comparison to Mr. Mansfield, but I say that because Gates grew up in the same shadow of the old tech companies (though maybe not as hippie; he grew up in a privileged environment in Seattle) as Steve Jobs and made a choice to focus on money instead of great products.
I use that term 'customer' deliberately because modern companies don't use that term anymore. Everyone is a 'consumer'. The change in that word means a lot. When we were customers, companies existed to benefit us. When we are seen as consumers, we exist to benefit companies.
And I think all of that, it comes back to the original matter -- do you go into business to get rich, or to make great things that will help people? I believe the world is better off with people who do the latter.