Private equity groups. Several have been brokering their debt restructuring over the years. Here's their most recent complete restructuring from about a year ago (http://www.insideradio.com/free/restructuring-will-wipe-bill...) (they're currently in bankruptcy at the moment.)

So what incentive do they have for "rape and pillage" of companies if they ruin them and themselves in the process?

Because the partners collect big fees on the way in and out.

Toys R Us is a great example. The PEG people invested 20%, dumped the debt on the Toys R Us balance sheet, and yielded at least $200M in fees. They are also able to harvest paper losses to offset taxes.

Pardon my ignorance, but who's paying their fees, and why would anyone pay fees to people who ruin companies and pocket fees for doing a poor job?

The acquired company. The people running the company are the people collecting the money.

Why would they do so? They are “turning the company around!”.

I'd guess "private equity $somethings"?