Hindsight is 20/20. What was Google when Yahoo turned them over?

At the time Google turned this down it was still completely unclear how they would make any money at all. The thinking at the time was that search was a more or less solved problem that had zero profitable potential (hence Yahoo becoming a "media" company). Only now, years later, does a company that sells ads on search results and makes cars that drive themselves on the side seem like a "logical" outcome.

This is the problem with trying to focus on working on the "important" things instead of the things that interest you: its incredibly difficult to know what will be important ahead of time. Who would have guessed that a strange abstract math that only dealt in 1's and 0's, originally invented in the 1800's would later be essential to powering every machine in the 2000s? At the time you could have rightly criticized Boole for having the luxury and privilege to focus on something so useless instead of using his time in medicine for example. Someone arguing that Boolean algebra would actually be instrumental 100 years later in machines that can cure diseases would have seemed like an absurd counter-argument.

When Apple was started the big computer companies laughed at the notion of a personal computer in every home. Steve Jobs' dream of everyone owning a personal computer is arguably one of arrogance and privilege: why focus on that in the 80s when there were so many "real" problems to work on?

Twitter is the epitome of silly privilege ideas: a company based around people yelling short sentences into the ether. Who would have guessed that would empower real time delivery of current events like a hurricane or a tidal wave?

No one knows what will be the idea that revolutionizes the future, but a lot of people do know what they're passionate about. If you focus on something you think is important but you're not passionate about, the result probably won't be great. If instead everyone focuses on what they're passionate about, we'll have a lot of top notch incarnations of an incredibly diverse set of ideas. Tons will be duds, but a few will change things, and they probably won't be the ones you predicted.

So why not accept that some people are interested in different things than you instead of trying to determine whether the owner of Snapchat is focusing on the right thing or not. You don't think its a great idea? Then go work on something else. The proof is in the pudding.

No one knew Google's potential when they were starting, I would argue the same is true for snapchat. Maybe they are nearing their full potential or maybe they're just getting started. Either way, that is big assumption you are making