You're correct in some ways but, I think, missing a few key points. For roughly 15 years before AWS, inexpensive shared hosting was available.
From a bootstrap perspective, there was little cost difference at the beginning. The main difference was in the middle stage: scaling. After a bit off success it was still possible and practical to scale until you outgrew the ability of a single dedicated server to handle a specific task. Until then, you could grow and scale with little difficulty from a shared server, then dedicated, then shunting functionality to individual dedicated servers, e.g., web sever, database, etc. Yes these cost money, but ig you were bootstrapping then you only got to that point after you'd passed through the nearly free-per-month shared stage and, abd long after revenue flow began.
Scaling beyond that was absolutely way more difficult in terms of tech knowledge and cost. Modern AWS makes that scaling much easier, but the pre-ramen profitable stage was not much if any more expensive.
The key cost that was then and still is the biggest, in my opinion, is opportunity cost. A hundred bucks a month then or now, with or without adjustment for inflation, is nothing compared to the opportunity cost.
As a more general rebuttal of the sentimemt expressed, I'd offer up "started in my garage" businesses of all sorts, then and now. Those whose primary initial input is never cash but sweat equity and grinding out the details and execution of an idea.