Another example:
We bought a house subject-to the debt, paid back payments plus let the owner live there for 5 more months. We had $15,000 of cash in the deal. It needed another $60k to rehab. The profit potential was around $70,000 cash. Instead of investing $60k more, waiting on the rehab, waiting on the sale, and worrying about the market changing in 6 months, we exchanged our position in the deal for a $50k 1st position note on a $100k house at 8.75% over 15 years at $500 a month. So essentially we bought a $50k note for $15k. The benefit to us is that we did not have to wait and we lowered our risk. The benefit to the note holder is that they cashed out their note a par.
This transaction was only possible because we did not need the cash. However we could borrow against our note or sell it at a discount to raise cash. We can also use it as a down payment.
In exchanging everything is money. It just comes in different forms with different durations.
These types of transactions happen on wall st all the time. They are just not something most people in Real Estate use.