Winklevosses were just a couple of deuchebags with an idea. Go to any Techcrunch/tech party in NYC, and you will meet plenty of them. They go nowhere, because they don't have the hard skills to make something a reality.
Ideas, are cheap. Given some beer, and one hour of time, anybody can come up with a dozen of decent ones. Execution on the other hand is hard. It takes sweat and real work to make something happen.
It's not a matter of the Winklevosses being "douchebags", or even "just coming up with an idea", which is false anyway as they had already developed the code and wanted Zuckerberg to finish it. They trusted Zuckerberg to deliver a product. Instead he held them back, while making his own version of their work. He screwed them over plain and simple.