people take jobs in private equity in the hope of cashing in personally. Typically, they have competence in a sector or an activity, but were getting only a wage, maybe wiht a bonus of some kind. Private equity gives you the possibility to do a very similar job, using the same competences, but letting you keep a slice of the profits you generate - usually the expectation is that you'll be earning several times your salary on top of the usual income.

Beyond the fact that most money to be invested in funds is already managed from London, you have the fact that this functions in English, most often using English law, and that the other players are already in London - that's where the game is.

And of course, for such big amounts of money, tax rates are more favorable in London (although it depends on your family situation: with kids, the calculation is not quite the same).

but essentially, private equity is where people hope to cash in on get-rich-quick schemes - this being driven by the asset price bubble (which means that I think today is not a great time to jump in).

In the long run, we're all dead. John Maynard Keynes