There are risks on both sides. A seller now believes you are buying their home. So they go out and find a new place to live. Maybe sign a new purchase contract, a lease, etc. But then you don't already have a buyer lined up, and you have no intention of buying it yourself.
So not only are they out of a buyer, but the new place they were to live in is now out of someone, etc.
Of course, I am not a fan of the practice of Wholesaling. If you go out and find cash buyers, why not take that time to go out and find cash lenders, cash partners, etc.
There is a wholesaler in an area I invest in, he puts bids in on listed properties to include HUD homes. Say a property is listed for 10,000 as a HUD Foreclosure. He bids on it, then out of now where, the area is over taken with Bandit "For sale" signs for that property asking $17,000 for it.
Many times I wanted to buy the property, but the Wholesaler, whom we will name "Dan", overbids. After a month or two, the property fails to close, and I buy it then.
I feel bad not so much for HUD, but for the Realtor that is doing that work with a person that doesn't close. IF I was the Realtor, and I saw all those signs, I would inform my client and have them yank the contract.