Regardless, i'm sure if you looked through anybody's comments in HN (including your own) then there is bound to be one that dismisses the next best thing as "no way this will work". Difference here, it's on a post with only 2 comments. If this had made it to the frontpage of HN then that comment would have been buried so deep no one would have batted an eye-lid.
Urban dictionary definition of hater: http://www.urbandictionary.com/define.php?term=hater
A person that simply cannot be happy for another person's success. So rather than be happy they make a point of exposing a flaw in that person.
Hating, the result of being a hater, is not exactly jealousy. The hater doesnt really want to be the person he or she hates, rather the hater wants to knock somelse down a notch.
I don't think his comments are really to do with not being happy about a persons success etc, it's nothing personal, he simply did not believe the idea would take off.