Some non profits have very well remunerated CEOs.

One of the reason why companies distribute dividends is that when a big pot of cash starts to accumulate, there end up being a lot of people who feel entitled to it.

Employees might suddenly feel they deserve to be paid a lot more. Suppliers will play a lot more hardball in negotiations. A middle manager may give a sinecure to their cousin.

And upper managers can extract absolutely everything trough lucrative contracts to their friends and relatives. (Of course the IRS would clamp down on obvious self-dealings, but that wouldn't make such schemes disappear. It'll make them far more complicated and expensive instead.)

If you don't have to turn a profit to investors, you suddenly can pay yourself an (even much more astronomically high) salary.

They usually pile up in a bank account of stocks and bonds or real estate assets held by the non-profit.

They call it "budget surplus" and often it gets allocated to overhead. This eventually results in layers of excess employees, often "administrators" that don't do much.

Or it just piles up in an endowment, which becomes a measure of the non-profit's success, in a you make what you measure, numbers go up sort of way. "grow our endowment by x billion becomes the goal" instead of questioning why they are growing the endowment instead of charging patients less.