I have problems saving money due to spending habits.

My idea is to buy foreign currency online and keep the money stashed away until I need it either for an emergency or for another investment.

The reason I think this would be good is that it stops me from easily spending the money but it also provides a potential emergency fund by exchanging the currency at a bank.

Another thing is the novelty of owning foreign currency might improve my outlook on wealth building and cause me to want more of it. So it would be a lot like silver stacking only more liquid and easier to store.

My question is... is there any downside to this? Would time be an issue? If I were to store the currency for more than three years would it still be exchangeable?