I take advice from rich people with a grain of salt. It's easier to praise the value of money over integrity when you have both. They don't ask starving artists to give graduation speeches.
Watterson appears to have genuine integrity and I applaud him. There is a point where you have enough money, and the ones who deserve the most scorn are those who cheat to get even more when they have orders of magnitude more than that. But don't forget that a lot of people really do have to choose between integrity and dinner, and I don't judge their decision.
It is my opinion that while you do not judge people who have to choose between integrity and dinner, you can definitely judge people who made decisions and structured their life in such a way that they had that choice, and not only did they choose money, but did it in such a way that what other people would call riches was subsistence for them because of the lifestyle they led.
> There is a point where you have enough money
You forego the option of choosing when you end up chasing a goal or living a standard of living which requires you to continuously choose money every time. It takes a lot of thinking to come to what "enough" means. For some, enough is a few hundred thousand dollars max. For some, even a billion is not enough. You can definitely appreciate the former when they reach that goal and stay there, but it becomes difficult to appreciate the latter (and they are the focus of most of the criticism here), because you do need to sacrifice more than a bit of integrity in that case.