Cops / military open carry because they already have the uniform, and the implications that has (legal use of force, training, and back up). Private citizens are safer if they conceal carry for a number of reasons, here are two:

Privacy. Some people get intimidated and / or think open carry is a political statement. Which it is sometimes, but not usually. If you open carry, it’s better to do in appropriate settings and with groups. Day to day carry, it is better to just blend in with the crowd.

Security/safety. If you open carry you need to be prepared for someone trying to disarm you or shoot you first, because they know where your weapon is, and that you have it. It’s not really worth the deterant value. In conflict it’s better to have the element of surprise rather than be surprised by someone who knows who has a gun, and where they are.