Simply not true. Just for one example, Catholic Charities is one of the largest charities in the US, with a significant international presence. Any social justice protest or march is going to have a lot of professed nuns and priests in it – you may not notice them, but they consider that they are practicing their faith. And any parish at all has some kind of ministry to the poor, food pantries, shelter the homeless, all of that stuff. You are misinformed.
That is what they are doing?
If so than I don’t see the catholic church speaking out about millionaires or a billionaires if it is sin to be rich.
The Church has never fitted into the simplistic left-right political spectrum. Catholicism has always been a strong opponent of communism, but isn’t keen on capitalism either:
That’s because they don’t think it’s a sin to be rich.
There may, of course, be moral issues that arise in connection with how you become rich. But being rich in itself isn’t inherently immoral. It does, however, raise the moral questions of (a) what you do with your riches, and (b) how you let your riches affect you. Being rich isn’t inherently immoral, but it is morally challenging.