Is this strategy valid?

[Jon Joro]

I have seen a scenario where a buyer put a property under contract for 70K but decided during Due Diligence wasn't going to buy it so ends up assigning the property, here's how it looks -

Property under contract for 70,000 and the buyer listed it for 100,000 with 30% owner financing. Found a buyer and payed the seller the full amount and holding a private mortgage for the rest.

Does anyone see any problems doing this?