One exception to the "solve your own problem" approach to startup ideas

I got an email from a founder recently who wanted to help create software so that you could find other cofounders. It's a common idea that is so frequently attempted that I usually try to dissuade people from working on it. This is what I wrote him: 

It is usually the right thing to create something you yourself would use. Finding cofounders is a common problem that founders face, but it is probably a special case exception to the guideline. There probably aren't enough people who want to do startups, and you won't be able to make enough money from those startups to actually support your business. 

I would suggest that you work more on things that a lot of people in your world can use. If you could pick anything, the ones that are most valuable tend to come from there. 

There are probably specific aspects of your local economy and markets that you know about that nobody else knows about. Make software to solve those problems. For instance, I've met founders in the past who have backgrounds in the an unsexy business like textiles, or manufacturing. They end up making marketplaces or management software that make those kinds of operations a lot more efficient, and they're the only ones who can do it because it is rare for someone who knows how to code who also understands all the ins-and-outs of that particular industry and use case. 

You can think of this being true for any economic activity: banking, real estate, retail, wholesale, shipping, food, entertainment, transportation. There is an infinite amount of software just waiting to be written, around use cases that people actually want and care desperately about. That's what you should focus on. 
This is an unusually ripe time for people to make software that touches late adopter industries like the ones mentioned above. 

It's not enough to be focused on your own needs. This is why empathy is so important as a founder. You really do need to focus on the needs of others. That's the path to creating something people want.