A few months ago I read that the average google engineer creates something like $50k/month in value for the company. He might get paid $150k/year if he's lucky, that's insane.
Most engineers at Google almost certainly do not drive $50K/month in revenue for the company given that Google properties generate a hugely non-uniform distribution of revenue. While the guys working on say Android or Gmail for instance might be helping Google's brand, they are a very small part of their bottom line (at least now).
If engineers are underpaid, start a company, pay engineers more to lure them away from Google, and enjoy your "paltry" ~50% profit margins.
As to your theoretical example of starting a company, here is where that falls apart logically. Several hundred families own trillions in capital. They make 20% a year profit on each engineer they employ. Say I own $50 million. I am a nice guy, so I only make 15% a year profit off each engineer, and give the engineers the other 5%.
Several things arise from this. For one, the dozens of people I employ are only a drop in the bucket to everyone else. So the dent in the whole economy is negligible. More importantly, my already relatively small pile of money is growing slower than everyone else's. Compound returns and all that. Now they get even more economies of scale. I can't even maintain my small niche, my small piece of the economy becomes ever smaller over time.
I don't want to go into every detail of your messages...anti-competitive? Look into the documents on the anti-poaching case which has hit Apple, Google, Intel etc. Also, there's a well known way for companies to make excessive profits - monopoly. Something the government is currently investigating in the case of Google.