If I play heavy games daily on my MacBook will it decrease its overall lifespan?

All electronics age. Capacitors are the worst, as they have chemicals inside. Power supplies are subject to heating, same with CPUs and GPUs as the chips run hot. Using a computer will shorten its life, but storing it on a shelf is not much better.
I'm trying to replace all capacitors in a failing 2004 iMac all in one 17 inch. My Lenovo G555 laptop had 3 video chip detachments, a common problem. Now trying a new motherboard. My 2005 LCD panel from Dell had fluorescent tube failures from heat. Bought new ones. Very likely. Mac is the best You're using something. It will eventually wear out. That's just the way things work.

Very likely.

Mac is the best

You're using something. It will eventually wear out. That's just the way things work.