Two parts to this:
1) why do you hunt?
2) why do you hunt with a muzzleloader, especially if you hunt exclusively with one?
1- I started hunting because it is a way a life where I grew up. I continue to hunt because it's the greatest escape from the every day pressure I face in the corporate environment. No other activity gives me the degree of solitude and peace.
2- I gave up centerfires about 15 years ago. For me, it was due to the lack of challenge. I reloaded for years but that really just delayed my venture into muzzleloading full time. There's just something about making that one shot count and knowing that you have more limited range and flexibility vs a centerfire.