Before owning a store, there was such a thing as having "faith in humanity." Most people were generally good and kind and well meaning. Owning a store showed how easy it it was for supposedly good people to become so-called "bad people," to steal and lie when the opportunity presented itself. The line is perilously thin between honest and dishonest. It's not some colossal battle of wills between an angel and devil on each shoulder. It's just opportunity.
If you haven't owned a store, there's no way I'll convince you this is true. There's no way I'll budge your faith. I accept that. If you do own a store, you know what I'm talking about. The familiar knife in the back. The smiling regular who spends a fortune in your store who you still discover steals on the side. The employee you took into your home who robbed you blind. The guy, now this story is totally true, who you catch walking out of your store with two hundred dollar army boxes under each arm, who blames you because his in-store D&D group is now down a player because you banned him.
When owning a store, there is no longer faith in humanity. Faith is belief and you now have demonstrable proof. The vast majority of people will make the wrong choice if given the opportunity. It's about 90%, 10% who will always steal and 80% when given the opportunity. How you engage with this fact determines how you'll view people going forward and whether you'll be happy or not. You will give up your Faith for a philosophy of trust, but verify. It's easy to become bitter when coming to grips with daily betrayal. If you want to own a store, know this loss of faith, this change in philosophy, will be a psychological price far higher than your initial investment.