That was an enjoyable read! I have also tried qutting my job as a developer, tried making money by working for myself (and focusing on developing features instead of actually making money, same as you), then returning to a "proper job" as an engineer. There were many recognizable moments in the blog post.
I once took a course in entrepreneurship, as a distraction from computer science, and the bottom line is that to make money you should first try to find someone willing to hand you their money, and then put the effort into making the product or service. But, as a developer, it's soul-wrenching and just feels wrong to try to sell something before something proper has even been made. But I've seen it work many times, you just need sales people that are not afraid of making up products while they go, with both the profit and stress that follows.
I'm glad you found a good opportunity with an accelerator, good luck with the next adventure!