As mentioned by Dark Gaming - Terraria Server Rules:
Is giving money to another user to hold for me so I can get < 5000 DP gain rate an exploit?
No.
Someone can hold other users’ money so long as there are no multiple accounts involved. This is not an exploit, I expect people to do this, and people should do this if they want so I can review what is and what is not working.
My expectation is that I will be meddling with the role of DP in the system to try to make all the currently out of reach things possible for people to get, this will inevitably mean that how people approach the economy today may change over time in response to changes I make.
These changes are not part of the next trading system, nothing major will change in that how you use the system will remain largely the same, the changes being made are just to move the current one into the place it needs to be so that there will be time to develop the next iteration when it is needed.