I got very randomly bumped up to first class on a transatlantic flight for business. I do not travel much for business, especially internationally. So, I definitely should not have had priority over more regular accounts. I have to assume I just got lucky, and that flight happened to have no frequent flyers.
It was an eye opening experience. I got to hang out in a secret lounge. When my flight was ready to board, multiple staff escorted us to the gate. When we landed, we took a private van to a secret side entrance, which had its own first class only passport check. We were brought to another secret first class lounge through hidden back hallways to wait for our connections. The lounge looked down over the terminal, and the exit was a nondescript door you'd assume was a maintenance entrance.
Being around that level of service and the other people in first class, it's clear the wealthy live in another world. I looked up how much that ticket normally goes for after, and full price is for many people a yearly salary. It was nice, but it seems like a crazy way to divide resources.