In my startup (until our exit) I've run Postgres on my own, with streaming backups, daily backup tests (automatic restores and checks), offsite backups and (slow) upgrades.

Data wasn't mission critical and customers could live with 5min downtimes for upgrades once a year.

No problem for years. When we had hosted Mongo, we had more problems.

If I have the money I'll use a managed database. But running Postgres in a startup up to $10m ARR / ~1TB data seems not like a problem.