In 2016 I've built a social platform where someone starts a photo thread and others reply with photos of their own. It was a complete social platform: messages, likes, facebook style grouped notifications etc. I've put all of my engineering skills to the table.
The most important thing it was fun to use. For example someone started a thread "What's inside your drawer?" the replies were... terrible, sincere and messy. People had peace with sharing their real lives we had the anti instagram aura. It created some hype at that time. Had 500 users. 2 people met at my platform and married.
It was the moment that I've felt "WOW I'm changing people's lives in a good way by writing code". I know it is a little narcissistic but I loved that feeling.
Then the time passed I've married too, had kids, could not keep up.
The development was getting hard for me (Think that you're writing complete social media in 2016 without AI, you have blog posts, IRC channels and StackOverflow), could not find any help or money to continue.
I don't remember exact time but I've shut it down. One of the reasons that I did not continue was the income model, which did not exist.
Years passed I've built other things, looked at numbers, market demand analyses, SWOT analyses, tried to build things that people need and would pay for. But something inside me was not satisfied. I was suppressing the artistic side of myself. Customer to product was not my path and understanding this took about 10 years. (I'm not a quick learner lol)
Building something must be an art IMO. When you're working on it you need to feel like you're painting or writing a story. SAAS tools does not give me that feeling. The internet is a communication device that you can define the game: how people interact with each other.
For me, it was photos, attached to threads. It was there since beginning I was just ignoring it. Now I'm building that again and I will not stop until I find some people who use it daily.