Oh for sure, I agree there are good and bad people on any scale of the economic level. Dolly Parton is an example of a truly great billionaire who is making a difference with what she is doing with her platform. I've also seen plenty of other people both small and average size use their platforms to do harm or for good too on a variety of issues beyond philanthropy.
It's more of the fact that when looking at most billionaires from this perspective, there's clearly something wonky about their charity. In the case of Elon Musk, yeah Space X is doing some good and the guy paid his fair share of taxes and donated to charity and has a foundation. But that was one year out of the dozens of years he's been a tax-paying citizen. I didn't dig much into his foundation but I wouldn't be surprised if it was just hoarding assets and only giving out a little bit to the causes it says it supports.
Obviously it's their money (aside from the cut that's meant for taxes) to do what they want with it. But I do think it's fair game to look at their actions with said money and the bigger scope of things. Elon Musk was the first billionaire to actually pay a reasonable amount of taxes relative to his wealth and people defend him because he did that this one time. As if that's the bar for being generous. The phenomenon interests me especially when for non-ultra wealthy classes are paying their full taxes every year and they're not getting praise for it.