Hey, Vmichail, thanks for playing and for your feedback.
Kobolds have 5-15% percent to drop a coin, depending on their class. They are kobolds so that's a low percentage. Enemies in later stages will have increased percentage. As feedback comes in, we can tweak those numbers if they are low.
However, with upgrades, you kill more enemies, so more chances of gold. Furthermore, when you run out of upgrades, the Coin compensation option appears again in your level-up menu.
Thanks again, let us know if you find anything else!

