I agree, there are a lot of “senior developers” who shouldn’t really be called that. Certain things you can pin point very quickly even from the first time you see them. Other times you need to listen to your team. Sometimes, however you need to back off and realise that you bring in experienced guys so they can tell you how to build stuff and scale as well. Sometimes your existing team is quite bad and they don’t even know it. Sorry but it’s true.
So yeah, careful who you hire and how.
As a founder / owner / CEO you will need to realise that you don’t measure performance by how long people stay at work. I know, big bubble to break right there and a lot of good seniors will laugh in your face if you expect them to work until they drop.