In some countries private law firms chase down infringers on behalf of copyright holders. They then attempt shakedowns with the threat of legal action if you don't pay. They have a financial interest to catch people, and moral compasses vary.

Also, mistakes can happen (you, your family, guests using your wifi, in the courts, in the ISPs, in the law firms, in the tech they are using to identify people). Shit happens.

And if (when) it happens, then you would still have to deal with it, costing you time and money.

Understand the risks and make choices to minimize them if you can.