One of the best possible outcomes: very cool new business idea, continues operating, backed by Google, with founders compensated for the risk they took launching it. Awesome news. Congratulations!
I didn't think he felt seriously offensed by the comment pointing out that the idea wasn't new.
The downvotes, well, those are, strictly speaking, justified. :)
Maybe you expected him/her to be excited about the exit but that not being the case does not mean you should have repled with 'rude sarcasm'.
You could have used the opportunity you used to respond to learn about competitors in the space however you chose this route.
I have noticed several senior (by karma) HN members that take an unecessary offensive approach towards comments that do not "tow the line".
We know you have FU money now but please remember that that expression is supposed to be figurative and not literal.