Who manages the managers and how do you trust them? How do you measure their value when it's possible to cook the books? A portfolio of managers seems less reli

Who manages the managers and how do you trust them? How do you measure their value when it's possible to cook the books? A portfolio of managers seems less reliable to me than a portfolio of companies. At least in the latter case, you can all pretend that the other investors are doing the proper diligence.