The government (and/or Fed) creates money. Stocks go up; bread doesn't. If I have to buy bread, I'm not instantly worse off. But if I own stocks, I'm instantly better off.

Why do stocks go up? Because the money gets pumped into financial institutions, and from there into financial instruments.

Why doesn't bread go up? Because the number of people who own large amounts of financial instruments, and who don't already buy as much bread as they want, is zero.

But this situation - they're suddenly magically richer, and I'm not - magnifies existing wealth inequality.