Yeah, I remember when AWS first appeared, and the value proposition was basically "It's expensive but you can press a button and a minute later you have a new instance, so we can scale really quickly". For the companies that know more or less the workload they have during a week don't really get any benefits, just more expensive monthly bills.
But somewhere along the line, people started thinking it was easier to use AWS than the alternatives, and I even heard people saying it's cheaper...