Killing 10000 monsters should have given him a lot of coins, right ?
I don't think 10K monsters is sufficent. Maybe 1 monster gives 0.001 gold?
It would definitely depend on the specific monster in question. The ones we've seen so far that had their monetary drop actually mentioned were only dropping copper coins, other ones we've seen didn't always have that laid out plainly like that. Since more often than not, 100 copper = 1 silver, 100 silver = 1 gold, and our only frame of reference is monsters dropping copper, we can't say 10,000 kills = 10,000 gold.
If the most powerful and rare monsters are dropping a gold coin or more each, finding 10,000 of them in a year or less would probably be quite a feat. Grinding the lower value mobs is perhaps more feasible, but again we'd need more info on their drop rates and how long it's taking to find however many of them.
