This is what happened at my last company. PE bought the company, grabbed the bank accounts, sold the buildings, rented them back, fired the executives (including me), tried to run the company on a shoestring (cutting manufacturing supplies beyond hurting), lost the biggest customer in the process, split up and sold the remaining businesses. A massive cluster and many of my friends were left scrambling to find new jobs. While some PE may actually be beneficial, most seem to be slash and burn.
I ended up getting a MEd and taught Math & Stat at a small college till retirement. Teaching was emotionally rewarding but not really financially rewarding. I did not care, I covered my bills and had a much calmer life.
I'm not sure I know of an instance where they're beneficial to anyone but the select few cashing out on the looting.
Another big scheme lately is buying up maintenance companies (especially HVAC) and sending out salesman instead of technicians. They'll buy up multiple companies in a specific service area and are now rolling out software where they can see if a customer has also sourced a quote from one of the other businesses, so they don't undercut their own price gouging recommendations. They keep the names so it still looks like a family owned business. The PE takeover has happened all over the Des Moines area. I'm not sure about the software implementation yet.
PE has only one concern and it's ROI. The consumer and workforce pay the price.