I have a rule that is simple, effective but also quite rude: if you can't deliver and maintain a 500 instances large infrastructure, same uptime and all, at half the cost of AWS by yourself (1 person) in 3 months using only open source solutions basically you should not have an opinion about this. You are just rationalizing your incompetence on this particular subject. Sorry to be this blunt but I am simply tired of…
I maintained a datacenter with approx 1000 hypervisors with a very small team and took few weeks to start having production workloads. The effort to maintain hardware was quite little and it was hugely cheaper than any cloud service. Having said that, your requirement is pretty absurd. Billions of people choose to own and maintain houses and cars and cook their own food because it's cheaper than the alternatives. Nob…
To be fair, there’s also nobody that would listen to them over a professional mechanic or cook.