I have a similar story, though from almost 10 years ago, so maybe things have changed. As VPoE for a small startup with mobile messaging apps (something like a couple million MAU and ~200M messages/month), I orchestrated a lift-and-shift from a top tier managed hosting provider to AWS EC2. The result was about a 60% drop in monthly spend on hosting. We used almost nothing except S3 and EC2, with some provisioned IOPs for our SQL backend.

That said, it was a long time ago, and I'm sure competition and prices have changed dramatically.