He found a repack on a private tracker. It was small, barely 50 megabytes. A standalone launcher replacement. He downloaded it, his anti-virus screaming warnings about "crack.exe" which, to the antivirus, was inherently suspicious behavior.
Legitimate players enjoy a smoother, crash-free experience. Crack launcher users spend hours on "black screen of death" forums. gta v crack launcher
Crashed every time you tried to take cover behind a car or switch characters (a famous bug in early 3DM cracks). He found a repack on a private tracker