Full disclosure: I've worked in PE before, though I do not currently. Did not directly do anything involving LBOs.

Companies seeking LBOs are not generally in a great financial position. As a result, they tend to go bankrupt at a much higher rate than would otherwise be experienced. Hertz LBO happened before Icahn (a HF manager) got involved. People like Icahn don't invest in a company to lose money — clearly he believed that the company still had value even after PE got involved.

You only hear about LBOs that fail. There are dozens that work every year

Do you know of any data referring to the success to failure ratio of leveraged buyouts?

The easiest way to do this is to look at the performance of LBO funds. It's up and down, returns are pretty poor compared to the stock market, but still positive, so that means they're getting back more cash than they are putting in - which means more success than failure, especially as success means +20 to +40% whereas fail means -80 or -90%

How many LBOs happen each year in the US? I would guess somewhere around a hundred. So dozens of success stories per year might be really good, compared to similarly distressed companies that did not get the LBO.