Is being naive believing everything someone says or is it closing your mind for security and "realism"?

I think that being truly naive is being so skeptical that you are close minded. When you close your mind, you shut off the potential opportunities you may have in life. Surely you benefit the security but you lose more than you could potentially gain. If you are open minded you can eventually claim the benefits that a close minded person would not. What would you gain closing your mind? Not being tricked. But it really depends. Most of the time you won't lose much. But having an open mind long term has better benefits. And yet you can still learn some information and you can still use common sense at situations. For example if someone you know has lied, do not listen to them if they speak of something similar as they are liars. Or if you have been fooled by a company, do not go to that company anymore. Being open minded and using your intellect will get you furthest possible instead of closing you mind and locking yourself in.