Will running my roughly 2 year old Ryzen 1600 at 75-80 degrees for a good 6-8 hours every day ruin the cpu?
No but I mean it could shorten its total lifespan.
Anytime something is running a bit hot, which 80c is about that acceptable zone that you dont want to go over, running it at say 65c, would increase the total life of the cpu. I mean there would even be a differance from 65c, to 45c on lifespan. However even at 80c, its fully safe and is rated for higher than 80c, its just any increase in thermals on any hardware will shorten its lifespan even by a very small amount but your more likely to upgrde the chip before it would ever die from any "lifespan loss" anyways.