My single on-premise Exchange server is drastically more reliable than Microsoft's massive globally resilient whatever Exchange Online, and it costs me a couple hours of work on occasion. I probably have half their downtime, and most of mine is scheduled when nobody needs the server anyhow.

I'm not a better engineer, I just have drastically fewer failure modes.

Do you develop and manage the server alone? It's a quite a different reality when you have a big team.