If it's your system, then only you have access to grant access to others. If you hire a sysadmin to build you a system, you make sure you trust that person, and

If it's your system, then only you have access to grant access to others. If you hire a sysadmin to build you a system, you make sure you trust that person, and make sure that person is the only one with access to grant access. If that person lies to you and starts handing out that access, you replace her/him. And if you can't find anyone trustworthy, then you're forced to do this job for yourself.