AWS is massively overcomplicated for an indie SaaS business, and it costs way, way too much.
You can have a box with plenty of room for $5 - $10 / month and it takes about 25 seconds to launch it.
I had 20k concurrent users with a $5 server and Cloudflare. Other people are using serverless solutions, which drive the price even lower.
The author stated as much: keep it simple and boring. He thought he was going boring for a SaaS, but he went way too exciting for what an indie SaaS needs.