I spent about 50K on mine which isn't too bad, but i still hate myself for it. I made it back the first week with a draik egg before they deflated so terribly.
At least you were able to make your money back! I haven't gotten anything good except 2k-10k >.> I always open my DTCs and have nothing to show for it yet lol
You can get Pirate Draik/Kraw MPs, Pirate PBs, Draik Eggs, etc from it. I think there's a list on Sunny Neo or if you just google "items for in a discovered treasure chest" something will come up