Renting is a waste of money and everyone (or at least a lot more people than at present) should own one's own home, whether on their own or via e.g. a housing cooperative.
AWS might cost more but it provides a lot of benefits that are hard to assign a dollar value to.
Those things are typically factored into estimates for ownership v. rental costs, and even with those factored in, renting costs more than owning. That really shouldn't be terribly surprising, either; if landlords only broke even on their rentals, then there would be no reason to be in the rental business instead of the property management business.
If I know I'm going to be living in a city for two years, buying a home would likely be a bad idea. Sure we could talk about scenarios of renting it out and yada yada, but we're getting into corner cases in a comment section of a thread about AWS pricing :)
And bringing things back to AWS pricing: yeah, at first you might not know exactly what you need capacity-wise, but at some point (assuming you're actually measuring resource usage) you start to get a feel for what you need day-to-day and where things are trending. Much like with living arrangements, infrastructure hosting tends to have at least some pieces that you know you're gonna need long-term.
The more compelling reason to go with IaaS/PaaS is the convenience of not needing to run your own servers in your own rack - and it's that convenience that you're paying for, at a premium compared to hiring sysadmins. For a lot of businesses that's cost-effective, because they don't have/need enough infra to keep a sysadmin busy, but at some point that flips.