That is a stellar deal for him because it is effectively a 0% interest loan and he is still banking on the appreciation. 

Conventional loan

My only other bills are phone, insurance, gym, and student loan.

Conventional loan

I see so many assumable loan which seems like deal, but I am unable to take it as my DTI is high due to primary property etc. 

I have a $375K  2.5% 15 year loan, paid off in 8 years.

Also, full disclosure - I have utilized creative financing & transaction structures (installment sale transactions, had the seller take back 2nd position notes, baked brokerage fees into the agrement of sale  in off market transactions to name a few), so I am not opposed to it, but they were utilized in very unique and circumstantial land entitlement transactions. 

,also, yes I see why you would have to sell a mortgage at a steep discount because there would be a tiny amount of buyers and not much market for it.also banks yes are allowed to loan up to whatever the reserve rate is and they can package multiple mortgages and sell them off. 

Does having the capacity to pull a business loan or business credit card benefit strategy in any significant way?

If you need an earnest money loan, Ping me.