And what exactly does the average citizen of the US gets out of this, given the above?

Not even the tax money of those "top tech companies". Heck, some of those come to us (e.g. Ireland).

As for their products, we can buy them just fine as well.

This. Facebook, Google et al are American but will do everything they can to lock profits in low tax regions outside the U.S and they're also hiring more and more outside the U.S If Facebook stopped being American tomorrow I'm not sure the effect will be noticeable.

anecdotal