Would it make any difference? I'm a UK citizen. If I earned profits from a VC fund in San Francisco what are the chances of me paying only UK tax on that? You can also tax the fund directly and the corporations they invested in. You can tax the transfers of wealth between those entities. Of course you can tax these people if you want. Sure some of them will run to Belize, but the US control the domicile rules, tax them as you wish. Are they going to stay there forever? Tax income earned on US PE funds at source. Do whatever you like.

It is frankley pathetic to suggest you can't tax rich people or they will go abroad.