Are you classifying third-party donations to their foundations as earnings? I find that disingenuous. Private income is not subject to limitations, oversight and disclosure as funds received by a foundation that publishes an annual report publicly. This is not what I interpret Clinton referring to when she talks about tax loopholes used by the rich, since there are tons of vehicles, especially in non-US jurisdictions, that ultimately let you control your funds and are not subject to disclosure, while acting as tax shelters.
If you bothered to look up their foundation's annual report, you would realize that they have significant restricted contributions and the endowment is a measly $55 million and barely earned 1.6 million last year on its investments. The vast majority of the program's assets is made up of funds earmarked for specific programs, funds invested in specific programs, and pledges and grants yet to be received.