Whether it’s an important consumer application, a specialist app to solve a particular niche problem, or even a time-wasting game you can play on your phone, you can create a massively successful business if you build software that helps people. (Look at the rise of Slack—the team communication software that went from side project to billion-dollar company in just 2 years.)
I have cleaned house, done dog sitting and sold items I no longer need. I have complimented my retirement income by about $ 1000 a year paying for a plane ticket, rental car, bed and breakfast, food and attraction tickets for a 3 to 4 day trip. It gives me something to really look forward to. I always pay taxes on the service income I make. Always give value.