No pay, zero tech background, poor English—I’m promoting my family's iOS app and starting to doubt "pure market research"

For the past month, I’ve been helping my family promote their iOS app in overseas markets. I’m doing this completely pro bono—I just want to do my best to help them, and frankly, to prove whether someone like me (with poor English and zero technical background) can actually move the needle.

Recently, the dev in our "tiny family team" assigned me a new task: research new app ideas. They want a pure business analysis—finding profitable, high-demand vertical niches so they can build them.

While figuring out how to deliver a market report that would actually impress a developer, I couldn't stop reflecting on a deeper question: Should we build apps solely from a business/monetization standpoint, or should we scratch our own itch first?

In my mind, when you build something to solve your own real-world pain point, you pour your heart into every single detail. You anticipate the friction because you are the user. That’s how an app gets its "soul" and long-term vitality.

To be honest, with the app I’m marketing right now (TankSync—an aquarium water quality tracker), I have never kept a fish in my life. Because of this lack of personal connection, marketing it has been an uphill battle. Technically, the app works great, but does it actually solve a burning pain point? Does it make fishkeepers' lives easier? We are still blindly figuring that out.

I’m not dismissing the value of market research, but I genuinely want to ask those who have built multiple products:

In the long run, do apps born from personal pain points stand a better chance of survival than those built purely based on market research? Or does the origin of the idea not matter, as long as the pain point is validated?

I would love to hear your thoughts and experiences.
Thank you all!