This is a miscommon myth in the game developer community. DRM can still be stolen, many famous games on steam got stolen even before it was launched (FF15 got stolen before lunch). So no matter what you do, it will always gets stolen, if you want to not let pirates use your games you better off hiring a team that will track down the internet and issue DMCA on sites. My free games get stolen a lot it hasnt been a year but over 100 DMCA take down have been issued. these robbers install malware/spyware in your game as well as use your name for a cover up.
Just a small lesson to everyone to learn, you can't always protect your game.