Discipline

No cage is totally secure. You are in a cage because you want to be.

Chastity is a decision you make. If a nut slips out, take the cage off and put it back on.

Of course you will "want" to take the cage off and flog your dick until you can't cum anymore. But you made a commitment to your keyholder and/or yourself. It's called discipline and like other BDSM kinks, it plays on your most important sex organ, your mind.