If you are going to keep your equipment for the long term, cost is not a factor. When you amortize the cost of equipment over the years, that $1500 rifle will add up to pennies over a lifetime.
That don't hold true with bows. New technology is always coming out. They cannot improve the firearm and has been basically the same since its beginning. Sure all bows are basically limbs and a string, but weight, speed and size is always being improved upon.
I guess to some archers, bows are like shoes for women:D