As a company grows, all sorts of new problems open up that your current employees might not be a great fit for. For example, you might not need a DBA when just starting out, but when your database reaches a certain size it might make sense to hire one. Or you might need to hire a middle manager once you reach a certain size - but all of your initial hires prefer individual contributor roles. Or maybe you need someone with a strong background in security to be able to pass an audit.

It doesn't mean that you hired the wrong people. Just that your needs are changing.