I don't expect you to comprehend any of this, but here goes:
They don't do that for billionaires or other members of the ruling class. Those guys get to keep the leverage assets.
They absolutely do, especially for loans against shares. Not only will they do that, they'll margin call your shares just because the value went too low -- whether you were making payments on time is notwithstanding. If you don't have enough to buy your shares back, they take your shares and flip them, which then turns it into a realized gain that you get taxed on. And if they're RSU/ISO shares, then you have other consequences on top of that, particularly a loss of future income. But for the fact that you can't live in your shares, it carries a higher risk than a mortgage does because all you have to be concerned with in a mortgage is paying the thing on time every month.
The advantage of taking out loans on your shares is that if you're confident your shares will increase in value, then you get to forgo selling your shares, which means potentially higher gains later than you have to pay in interest. If those shares do increase in value, eventually they get sold, so not only do you have higher earnings, but the IRS also gets more taxes out of you in the long run, the only thing is it comes much later.
I personally have operated under a similar theory but without taking out a loan, namely I underpay my taxes and just eat the 7% interest the IRS charges me, because the share price increase will greatly exceed that percentage if I had accepted the share withholding, where I lose the shares outright. And guess what else? Both me and the IRS get more out of it than we would have otherwise.
Regardless of whether you take out a loan or not, taxes get paid on any proceeds as soon as ownership is transferred.
Trump went bankrupt multiple times and nobody ever seized much of any of his property.
Two reasons for this:
1) He never filed for bankruptcy
2) It wasn't his property to begin with
His businesses were all set up as corporate entities, which isn't unique to him or billionaires or your "ruling class". You can literally create an LLC for $100, which while a fortune to you, isn't to a typical wage earner. That LLC can then own properties. If the LLC is insolvent, it can file for chapter 11, which is debt restructuring, not asset liquidation. That's exactly what he did, multiple times, keeping creditors at bay until the businesses were profitable again. Individual wage earners can do basically the same thing under chapter 13, but Trump did not.
They live in an economic system completely different than the one you live in.
They definitely live in the same one I and everybody else does.
The fact that you don't comprehend how any of it works is why you're kind of off in your own little reality, which you share with exactly nobody.