Generally it's down to self-interest, and depends on your class, race, gender, sexuality, and so on. People tend to have the ideology that benefits the demographic to which they belong. The Hoover Institution largely exists to further the interests of rich white guys, that's its purpose, that's why members of that demographic fund it, so people who belong to, or are products of, that demographic, tend to be drawn to work for it.
The US is a bit different from Europe in that racial group self-interest seems to generally take primacy over class identity...but sadly it seems as if Europe is going the same way.