Nice narrative style and congratulations on achieving your (first?) failure without too much trauma.
It's possible you invested your own money prematurely, possibly without talking to enough people about the opportunity. Your metric for how much people want something is usually directly tied to revenue, or if you are using engagement as your metric, you should have figured out some way to make money off of it before you invested in development. I suggest that other engineering-minded founders think of sales like writing "hello world" -- for example, if you're doing a physical consumer product, you can start by shipping pet rocks on day one.
More than just identifying a product people want, you also want to find a network effect or viral marketing approach so you can grow with a sustainable advantage.