Yeah absolutely!
Risk-Reward ratio makes games fun, imo.
Your game's reward is digging up stuff to make money, but there's no risk.
How I assumed it would work when I was playing was that you have to be thinking about 2 things when deciding the path downwards that you'll carve to get objects:
1. How do I get to the objects?
2. How will I be able to climb back to the surface with them so I can sell them.
I think this challenge would make the game even more fun. It would make you think more (rather than just mashing click :), and would give some enjoyable anxiety around "oh no, I dug pretty deep, will I be able to make it back up to the surface?"
This could enable 2 further changes: hide more vaulable objects deeper in the level (greater reward, but greater risk in the form of difficulty getting back to the surface); and secondly, have there be some punishment if you're unable to make it back to the surface -- either losing the items you gathered, or losing them + losing money for the "extraction bill".
Hope that this makes sense, but lmk if I can clarify any of my thoughts!