You pay with your data, the security of your device, your money (if hacked), and your time (cleaning up viruses). Furthermore, you contribute to an ecosystem that undermines the creative professionals who work thousands of hours to entertain you.
When a high-quality print of a film leaks on www.movierulzhd.com on day one of its theatrical release, the box office collections plummet. For a small film (an independent indie or a low-budget regional movie), a piracy leak can end its run entirely.
If you have already visited sites like this, run a full antivirus scan today. Change any passwords you may have entered on those pop-ups. Stay safe, and stream legally.