To put it simply.
Right now, the reward is like, 250k (a lot of gold) and a Randomly rolled belt. This, in my opinion, that last bit, is a big problem.
So, perhaps, the beast fight could see an adjustment.
Make it harder, reduce the money gain, but let us repeat the fight every X months (but please do not re-introduce permadeath)
Main reason is of course to get a chance to re-roll the belt, because while i personally keep getting a dual-stat with +3 disc from get go, every single damn time, somehow, i keep seeing other ppl getting, like, +1 disx +1 str and /nothing else/ and frankly it brings me pain. Especially considering that radiant heart ring, which is like, surface counterpart, is customizable with it's properties if i remember correctly.
Granted, there could just be... Other options. Perhaps ability to somehow choose properties on the belt, and making it static in that regard?
With added bonus of having to re-fight some bosses if you want to change a specific property? Something like this?