D&D 5E Help - I Over-did It!

[mburkom]

Lots of thought provoking ideas here in discussing how to spend that cheddar

 

[Eis]

the obvious answer to your problem is to do some meth and TPK....voila! No more problem!

 

[Kye You]

A thieve could steal the gold and that starts a quest to try to retrieve it. Alternatively the party could discover that the gold makes them a target to various vagabonds and bandits thus a whole adventure could come from the party just trying to get to a bank.

 

[Baldurs_Underdark]

The nicest way is to tie it into the quest. But if that is not possible, and if allowing them to keep the cash is not an option either, then let them use the money.

Game mechanics tells us to allow them (if you're nice) or force them (if you're a bully) to burn up that cash on replacable, consumable items. Think for example about healing potions, rations or help from NPCs.
DON'T allow them to spend it on unique/magic/special items. Then their wealth is converted into power.

For example, you could sell them some regular healing potions. And then just add one extra encounter in the next dungeon. They will drink the potions, and the wealth is gone. (And if that gives them too much XP, then just skip the XP of the encounter...).

Extra credits made a nice video. If you wanna get straight to the solutions for your problem, start watching at 4:40.
https://www.youtube.com/watch?v=W39TtF14i8I