I had a graphing calculator website that had 250K monthly active users, from the logs it seemed mostly schools' math classes in Latin America. It was running on a single AWS EC2 Classic.

Ironically, when I started working for AWS, I always felt threatened with sticks and never had space to maintain my own projects. When they deprecated EC2 Classic, my site went down. I didn't get time or mental space to migrate it.

Cest la vie I guess.