Same reason I only load .44 specials today, and stocked up on factory .44 specials to get the brass, eventually. I have 3 .44's, only one is a magnum, and will never shoot a magnum in it.
Love my 500!
500 grain Hornady load. Neck shot.
I once shot a Desert Eagle .50.
By your logic, why have a nice house when a cave will do, why have a nice car or truck when your feet will carry you? Why buy more expensive clothes when yard sales or dollar general will do? Why eat anything else besides peanut butter? Why bother with 22 when 357 can be loaded anemic to astronomical? It’s because we can, it’s fun for some folks and variety is the spice of life.
You pay the price later in life. Like yourself, when I was in my 20’s-30’s bigger was better. I’d often shoot 100-200 44mag a week. A friend had a 454 another 50ae. Trying to get double taps on a pepper popper was a challenge with the 50ae. I’ve tried the bigger 45’s and 50’s. At 53 my limit is the 44mag and that is not 100 per range session any more. The arthritis is more than willing to tell me when to stop. Enjoy them while you can nothing last for ever.