Oh, were you not alive when Steam started being a thing and piracy sharply reduced? Turns out people like to buy things from people who make things they like.

You can, but you'd use more DRM and server components. In the extreme your game would be streaming on something like GeForce Now so only paying customers can access it.

To a large extent we also see that today (because let's be honest, current copyright law is not enforced very consistently) and there are still big-budget movies and games being released.

Copies of GTA 6 won't work online, which is what the vast majority of people are likely going to be buying it for. Lack of copyright also doesn't mean lack of sales. GTA 5 was a huge commercial success despite being cracked in days.

I pay for Tidal and buy 99% of my games despite having access to safe private trackers. On the other hand I pirate 100% of my TV and movies. Make of that what you will but for me it's always a service issue (or lack thereof).