Problem: People make mistakes and markets change overnight, and someone's hard work via currency can be wiped out. While banks let users make accounts to mitigate how much they can lose, few know the feature, and it still isn't ideal.
Solution: Allow a limit for a shop such that if you fall below X currency the shop will stop buying product OR turns off.
This is a huge pain point for new players to lose days or hours of work due to a simple mistake and come in with nothing.