RDR2 was released in November of 2019 on Stadia.
If he played every day, it would be about 5 hours a day.
Assuming he took 2 days off a week:
152 weeks since release
152 * (5 days per week) = 760 days
24 * 760 = 18240 hours
6000 / 18240 = ~0.33
.33 * 24 = ~8 hours every day.
That's not a game, that's a job.