This former banker taught himself a new platform, realized an idea, and created a game that obviously many people are entertained by. The real-world impact? He got to quit a job he (apparently) didn't like very much, created a product that entertains people, and got to start his own company.
What real-world impact are you looking for, exactly? What's the "next big problem?" Should we all be trying to cure cancer? Save the environment? Create true AI? This may come off condescending, but I truly do want to know.
I have yet to find a single useful Facebook app, but that doesn't mean there are no apps which other people, perhaps thousands, consider to be useful improvements. Presumably, every successful product solves some sort of real world problem for some number of people, otherwise why would anyone pay for it?
Seriously, what should I be doing instead? I'm not smart enough to create SKYNET and since I'm not a pharmaceutical company there's no money in finding the cure for cancer. If entertainment and "poking" aren't enough for Tim and you, then that's on you guys to do something more with your lives. As for me, I'm perfectly happy to help people find cheaper tickets.