No one has won billions of dollars on GPL enforcement. It's not how courts work. Contrary to popular belief, courts also won't compel compliance (e.g. releasing my code); if I break your license, the standard recourse is damages, whether that's GPL or All Rights Reserved.
Otherwise, I'd make the First Born Child license, whereby by using my code, you give me full ownership of your first born child, your home, your car, and your bank account. I could write a license like that right now, but I couldn't force you to give me your child, car, bank account, and home. If you used my code, you'd have the option to accept the license and give me those things. Or you could reject it, in which case, it's a normal copyright violation; in that case, whatever I wrote in the license is moot, and you pay damages (and stop using my code).
The only part which wouldn't be valid in a contract was the first-born child. That was a joke.
Indeed, if the GPL were a contract, courts might compel compliance.
However, the GPL is not a contract, it's a license. The FSF bent over backwards to make sure the GPL/AGPL licenses wouldn't be viewed as a contract, in part to limit liability / damages / risk.
Confusingly, some EULAs are framed contracts, contrary to the acronym, and do expose users to much more risk of liability than the GPL.
The relevant part of the GPL is:
You are not required to accept this License in order to receive or
run a copy of the Program. Ancillary propagation of a covered work
occurring solely as a consequence of using peer-to-peer transmission to
receive a copy likewise does not require acceptance. However, nothing
other than this License grants you permission to propagate or modify
any covered work. These actions infringe copyright if you do not accept
this License. Therefore, by modifying or propagating a covered work, you
indicate your acceptance of this License to do so.