You can get an awful lot done with Go, MySQL or MariaDB, FCGI, Apache or Ngnix.
You start with one server on shared hosting for a few dollars a month. Then scale up to a dedicated server, if the load appears. Then scale up to multiple servers with a load balancer. Replicate the database.
On the load side, if you're accumulating "statistics" about user behavior, do you really need them for every user? Maybe only one user in a hundred. Or a thousand.
When you exceed the limits of that, you're a big company and can afford AWS.
A few years ago, we had those guys with the liquid meal (not Jucero, the Soylent guys) boasting about their "infrastructure". Not for making the product, for their web site. From their financials, you could calculate that they were doing about four sales a minute.
Their "infrastructure" could run on an Raspberry Pi.