Working at a non-tech regional bigco, where ofc cloud is the default, I see everyday how AWS costs get out of hand, it's a constant struggle just to keep costs flat. In our case, the reality is that NONE of our services require scalability, and the main upside of high uptime is nice primarily for my blood pressure.. we only really need uptime during business hours, nobody cares what happens at night when everybody is sleeping.
On the other hand, there's significant vendor lockin, complexity, etc. And I'm not really sure we actually end up with less people over time, headcount always expands over time, and there's always cool new projects like monitoring, observability, AI, etc.
My feeling is, if we rented 20-30 chunky machines and ran Linux on them, with k8s, we'd be 80% there. For specific things I'd still use AWS, like infinite S3 storage, or RDS instances for super-important data.
If I were to do a startup, I would almost certainly not base it off AWS (or other cloud), I'd do what I write above: run chunky servers on OVH (initially just 1-2), and use specific AWS services like S3 and RDS.
A bit unrelated to the above, but I'd also try to keep away from expensive SaaS like Jira, Slack, etc. I'd use the best self-hosted open source version, and be done with it. I'd try Gitea for git hosting, Mattermost for team chat, etc.
And actually, given the geo-political situation as an EU citizen, maybe I wouldn't even put my data on AWS at all and self-host that as well...