I'm sorry but you are woefully underinformed on the financial strategies of the wealthy. Billionaires do indeed take out loans backed by personal assets. In fact, I'd be willing to bet that the richer the person is, the MORE LIKELY they are to back a loan with personal assets (due to a number of factors, but a big one being that they typically tend to be comparatively "cash poor".
Take billionaire John Paulson (according to reuters, his net worth $11.4B). "Billionaire investor John Paulson has put up part of his personal fortune as collateral to back a credit line for his $18 billion hedge fund Paulson & Co., a government filing shows."
"It is not unusual for wealthy individuals to pledge part of the their fortune to secure credit lines. In 2014 Goldman Sachs, for example, provided a credit line to billionaire investor Steven A. Cohen, who pledged his massive art collection as collateral."
[SOURCE:
https://fr.reuters.com/article/us-hedgefunds-paulson-idUSKCN0V423R]
Heck, Elon Musk has recently been widely reported, as have many other billionaires, to be "cash poor". Typically, these billionaires have huge stock portfolios and thus can use their personally owned stock as collateral (much like Musk, Zuckerberg, Bezos, etc. have all done). There's essentially no difference between putting up stock as collateral as say real estate, artwork, cars, etc. as all are just personal assets. The biggest difference is the liquidity of some assets versus others, but that's a whole other discussion.
It's also very common (and has been for quite awhile) in tech industry investing as there are a lot of "paper wealth" people that are illiquid (like if you own a lot of shares of a private company that's worth billions, but don't want to sell your ownership equity, and there is no stock to be sold because it's pre-IPO).
"Chase says one of the biggest demands among his clients is for the ability to borrow against pre-IPO stock. Sometimes Morgan Stanley is able to structure loans against this stock; other times Chase combs his clients' holdings for other collateral to lend against."
[SOURCE:
https://www.forbes.com/sites/antoin...-boom-rich-wealth-management/?sh=67111a866f09 - That's a good article to read to get a basic grasp of just how prevalent "wealth loans" are ($70B in 2017 at just Morgan Stanley alone. Goldman Sachs has gone from $0 to $30B in funded loans to the uber wealthy just over the last 10 years or so)]
Rich people borrow, rather than pay "cash" because it's a good strategy for multiple reasons:
1. When you’re borrowing to finance an investment, the idea is that that same investment will pay back the loan, and leave you with your accumulated wealth untouched. Another reason to borrow is to avoid digging into your savings or avoid having to give up on valuable assets.
2. When you take out a loan, you're not selling your assets — you’re borrowing against them. This basically means that you are putting to good use the value that you own, without losing it.
3. By securing the loan with valuable assets, you typically will get a better rate and/or terms. Even though the person could get the loan without collateral, by securing the loan they can procure better loan terms (which can make a HUGE difference because the size of the loans they take are so large)
TL/DR: It's surprisingly common for the uber rich to get loans that are backed by their personal assets, as then they don't have to sell the asset.