One of Hipmunk's founders spoke to a course that I was in about their experience as a founder and how they were running their business. A few weeks later, a well known founder of another travel search company visited the class and said outright that if Hipmunk did have any success, that they would copy those features and that Hipmunk couldn't threaten their position. That is exactly what happened.
To boot, Hipmunk was acquired and shuttered by another travel conglomerate.