They definitely will. JP Morgan for example charges SOFR+1.85% for 10M+ accounts[0], which is better than the mortgage rate they offered me. Or depending on what you mean by wealthy, you might be able to afford having someone get you a better deal by trading on the markets (e.g. selling SPX box spreads) assuming you don't have the expertise to do that kind of thing yourself/aren't interested in doing your own wealth management.

[0] https://www.jpmorgan.com/wealth-management/wealth-partners/l...

Why would you borrow money and use it to buy a house and leave it vacant? Now you're paying interest on top of everything else. Do you think wealthy people just light money on fire for no reason?