From what I've seen there seems to be three main paths to being a successful indie entrepreneur:
1) The "Maker" Path: you slowly improve your own skills and reputation as a developer (or designer) until they give you a big enough advantage that you can translate them into a successful product. This usually means first growing an audience through blogging, conferences, courses, etc.
2) The "Marketing" Path: you become so good at the "business" part of your business that the you're able to launch new products from scratch without a preexisting audience. It's tough to know if this really works or not but I assume with all the money spent on Google Ads some of it has to work… right?
3) The "Idea" Path: you have an idea that you believe in so much that you'll basically stop at nothing to make it work, even if it takes years (which it probably will). You usually pick up the other skills along the way.
I feel like the poster here suffers from not quite fitting in any of the main paths: they did not seem to have a large pre-existing audience or network to launch to, hate anything related to marketing by their own admission, and their ideas –while perfectly good products, such as https://nomadmail.io/– do not seem to be the kind of project that would inspire the kind of passion necessary to sacrifice years of your life.