I'm not the OP, but I think your comment underestimates the power of the government if it were actually brandished against these people. The government has far more resources than any billionaire and if its levers are pulled in the right order, it could do far more than insist upon itself.
The problem is an extended period of relative peace, wealth and success has not (yet) been conducive to those levers being pulled. But it's coming. It's inevitable, because wealth cannot help but create its own demise. We last saw it during the Great Depression, the hangover of the last Gilded Age. The robber barons of that era did precisely the same thing the modern ones are doing, and they looked similarly invincible.