I have looked in to this company quite extensively because it is an interesting concept. However, they have a lot of bad reviews. In the comment section on most articles I read and the reviews on yelp as well as other sites they are filled with unsatisfied people.
From my reading, the initial offer is not bad and is roughly 5% lower than a broker estimated net. During their inspection process though people get hit with repair costs in the several thousands or renegotiating of the contract price. The other problem is that some of the sellers have gotten upset because opendoor didn't do the repairs that they charged for prior to relisting.
One of the benefits they market is knowing your net ahead of time but almost everyone says they did not close with the initial offer.
I don't see how it is a risk for retail brokers as most sellers are looking for the highest net. From reading the reviews it seems most retail sellers think opendoor is trying to pull a fast one as they don't understand the idea of wholesaling a house.
I also don't see how they would hurt wholesalers either. It's like CarMax, people still trade in their cars to other dealers at wholesale prices even though CarMax practices a similar model.
What I don't understand is how do they operate on such thin margins if the market shifts to a buyers market or even just a softer sellers market? Even with their repair costs and market risk fees, once they have to start being even more conservative wouldn't they have less interest in their offers?