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.