A treasure hunt in the game takes a long time and is not very lucrative.
The consequence of this is that in the later game you actually do not search for treasure anymore because it is not really worth it.
I now have over 900
You can spend up to 5 treasure cards to increase the yield.
Each additional treasure card gives a 25% bonus on normal earnings.
With 3 cards you would have + 50% and with 5 cards + 100% bonus
This would make the treasure hunt more rewarding in the later game.