http://hn.vernccvbvyi5qhfzyqengccj7lkove6bjot2xhh5kajhwvidqafczrad.onion/stories/36820105
Institutions trade at actual exchanges, pay fees for trades, fees for connectivity, fees for market data, etc. Institutions can have advantages with eg cheaper financing. I think most of what you have written is basically false, at least for US equity markets.