It is only fine if you are running your business on the assumption that people can and do leave for different reasons and you plan or adjust for it. A startup

It is only fine if you are running your business on the assumption that people can and do leave for different reasons and you plan or adjust for it. A startup I worked in struggled because someone had been given too many shares and then the CEO wanted them out but didn't want to leave equity with someone who wasn't working there any more. If they had planned that in from the beginning and not been so quick to hand out large equity amounts, they could have much more easily fired them and moved on. Same issue with people who can't do their job for whatever reason. If you don't realise that is a possibility, then you don't think of success measures, targets etc. and so they end up staying too long before you realise they are not working, at which point it is even harder to get rid of them rather than saying up-front, "we expect X within 3 months". Another blog I read recently said your hiring process is number one priority bar-none and I think I agree. So much of success is down to the right people that you need to consider all of this before your first hire.