Career Mode Money Glitch

Yesterday, I traded in a car for a cheaper car, and I somehow got money for it. I only realized today that this could be exploited.

1) buy car
2) trade in for cheaper car, get money
3) repeat for near infinite money

 

Well, if you sell something for 5 dollars and buy something else for 4, then of course that you profited, that's how simple math works

But then again, what if you ran out of cheaper cars?

 

oh wait i just realized realized that
silly me!
--- Post updated ---
I still don't think that dealerships should give you money for buying a car. Trade-ins are supposed to offset the price. I think the value of the car should decrease after some set amount of time [or mileage], to help prevent this from happening.