Two figures stand chained at the neck, and the loops are far wider than their necks. They could step out. That is the whole point of this card — not trapped, staying.
The Devil usually marks something you cannot seem to stop. Drinking, spending, a relationship that takes pieces off you, a job you should have left. The shared feature is that every time is the last time, and every time there is a reasonable-sounding reason.
The cold part is its assumption that you are getting something out of it. People do not maintain habits that pay nothing. It is easier, it is familiar, or stopping would mean facing something else. Plans to quit by willpower alone usually fail because they skip this.
Reversed, it is one of the rare cards that improves. You have noticed the chain is loose; a foot is already out. But the way out is seldom walked alone. Read this inverted as: asking for help is not weakness here, it is the method.
Reading the Devil as an evil person or a curse misses. In the image the chains hang loose enough to lift off. The binding this card names is mostly voluntary. It is not that you cannot cut it — some part of you does not want to — and admitting that is where the reversal begins.
With the Lovers the binding is relational. With the Magician it reads as capability being spent in the wrong place. The Devil never names its own object, which makes the neighbouring card unusually important.