They “sell” stuff to closely held entities and then lease them back. The principals take a vig from everything.

It’s not always an objective for the target company to go bankrupt, but if they do, the management has already pulled their money out. A company I worked for was a cash cow used to borrow and buy 3 other companies. The combined entity grew due to some growth hack stuff and one-shots, then got acquired. The PE boys made a lot of money, and the company itself was pretty much toast after the second acquisition.