there is the problem of getting that last 10% of reliability. In my experience, that next 9% will take 9 times the effort. And that next 0.9% will take 9 time

there is the problem of getting that last 10% of reliability. In my experience, that next 9% will take 9 times the effort. And that next 0.9% will take 9 times the effort. And so on. So 90% is very far off from 99.999% reliability. Which would still be less reliable than an ec2 instance.