Here's the gist: it's not that posting an opinion online is hubris, it's what your opinion entails and is based on. You have no facts about the deal, and no qualifications to speak on good business acquisitions. You call the product "worthless" while teams of people at Facebook and Google seem to value it very highly. I'm going to have to assume that the people FB and Google hire are all very intelligent and capable at their jobs, and they see value in purchasing the company (which is why they made the offer). You, however, with no information have decided they're all morons and you know better because SnapChat is "worthless". That, my friend, is indeed hubris. You assume that you know more than everyone else who has far more intimate knowledge of the company and product.
Here's the moral of the story: just because something seems "worthless" to you doesn't mean that it has no worth to anyone else. If other highly trained and educated people say it's worth quite a bit of money, then, perhaps, you should re-evaluate your viewpoint.