Lots of men are into tease and denial, especially the denial part. They want to be denied orgasm, teased and tormented to the point where they have blue balls. Many can’t trust themselves not to cum unless they have their cocks locked up in a chastity device. I will never forget one day I talked to 6 different men wearing them, that was a record. That many are wearing them around under their clothes.
Some are worried if they wear them for extended periods and have to go on a business trip or something that at the airport they will be discovered if there’s metal in the chastity device, they’d be embarrassed if guards or customs officers saw them. Nothing illegal about that, just the embarrassment factor of having everyone know your cock is in lockdown.
Some are apparently not always in them by choice. They have Mistresses that have placed them in the chastity devices for their own good, to teach them humility and control. It always was amusing when they had the ones with the sharp points on the inside to dig into their cock if they became aroused and their cocks grew hard and larger. The spikes would inflict pain and punishment for daring to become aroused. No matter if it was perhaps because Mistress was riding your tongue at the time! That’s part of the fun, to get them aroused while they are wearing them to further frustrate them and drive them insane and get blue balls.