In theory, if it's voluntary, every rich person could decide to give exactly no money each and every month.Yup. That's exactly my position. If you don't want to help save the world, then there is absolutely no obligation enforced upon you to do so.
Just don't expect anyone else to consider you in any way, moral.
And this is what I am challenging.
Since your thread is about morality, why would you consider a rich man, who chooses not to give to charity, immoral? How do you know there aren’t other reasons why he made that choice? Why does it have to be immorality? He could be investing it, perhaps creating new businesses even. In this case he is simply participating in the market, not charity. He can’t afford the charity right now, even though he is rich. If he decided to give, he wouldn’t be able to create. By creating a business that will produce wages, and perhaps products that will make everyone’s life better, he is immoral? Why must he choose to do what *you* think he should do in order to be moral?