Venture Capital firms love to use throw debt at an asset so that they can have a cash windfall. The result is that the assets can never pay off the debt and end up declaring bankruptcy.
See K-Mart, Sears, Toys R' Us, and anything that a vulture capitalist touches.
Venture Capital firms are early stage private investors. They don't do LBOs with dying companies, since that would naturally be a late stage investment. You're probably thinking of private equity.
Your view of how LBOs work is really misinformed. You picked 3 famous PE deals that failed, but those are exceptions.
Apollo alone has done 150 private equity transactions, the vast majority of which have been tremendously successful otherwise investors would not be giving them more money to continue to invest.
A lot of PE follows a well-understood playbook. Buy a player in a settled industry, cut costs (== reduce maintenance, make the workforce cost less, etc.) and milk it for as long as possible.
That tends to work for investors; customers and employees, well.
The Artist Formerly Known as SolarWinds is PE owned.
