Why is gta 5 free on epic games?

I looked at epic games one day and I realized it is free does anyone know that because I have been wondering this for a while.

No, it's not free, I'm talking about premium edition. But it's on sale, so it's cheap atm.

It was free for a while but not anymore, they often offer games these days though.

Probably to get you to try online and then pay for in-game currency