The problems faced by businesses aren't actually any more "real" than social apps, they're more
differentiated. What tends to happen as you get older is you start digging deeper into specific fields. Instead of looking at everything from the glossy overview perspective, you end up looking at the details, and finding specific tasks that can be done more efficiently.
I suspect this is why younger entrepreneurs tend to build bigger companies, but have a lower chance of success. The size of an eventual company comes from the size of the market it's serving. Basic needs - food, socializing, sex, information, transportation - are shared by nearly everyone, and so the markets are huge. But everyone can see any problems that arise in those areas, and so the competition to win the market is intense.
Building something like software for petroleum geologists working in undersea basins is a much tinier market, but many fewer people have the requisite domain knowledge to even understand what the problems are. So your chances of success are higher, but you aren't going to strike it big like Facebook.