It sounds like you spent 4 years building a product before you even knew if anyone would use it. That's a terrible idea, but a good learning experience.
I wouldn't give up (perhaps you need to give up on your current product though).
What you need to do is evaluate _why_ the product isn't selling. Who's the ideal customer? Can you get on a call with some of them and put it in their hands and get actual feedback? Figure out if you need to abandon the product or not. Stop building. Focus entirely on marketing and sales.
Next time, don't go so deep on the building phase until you have people handing you money.
For reference, I recently came up with a new product idea. I did some searching to figure out if any competition exists and I found none. That's horrifying. I almost immediately gave up the idea entirely on the spot.
However, I randomly met someone that was an ideal customer (while dropping my kids off at school) and they immediately said they would pay $200/month for that and asked when they could try it. Not only that, they said they knew 2-3 other people that would as well. I ended up meeting two other ideal customers that said the same thing and one even asked if they could invest in it.
I'm still not entirely sure-- but those are strong signals that people will put up money for it, but it doesn't mean they will. I am still nervous but decided to go ahead and build an mvp and see if the idea has legs.
What kind of signals are your ideal customers giving you?
1. Take all of the side projects that are too niche and/or unsellable and polish up the code then open source it (add it to your portfolio/resume).
2. Take the projects that are sellable and publish them in places people can find them (app store, on the web, etc) then put it on your portfolio/resume.
3. With your beefier resume/portfolio in hand, find a job.
Coding is quite subjective. When I examined the early bitcoin code (the one Satoshi wrote and shared). The C++ code looked pretty sloppy and amateur-ish.
The comments were odd and not standardized (randomly using four //// sometimes, etc). The use of 4-6 random new lines between sections of code was awkward. The way the code was organized, folders named, etc.
The code itself was a mix of hungarian-isms. It felt very academic-y to me... like someone that did most of their coding in university as a teacher or phd candidate (little real-world coding).
There's a podcast (name slips my mind...) where the host asked Bram Cohen if he thought Len was Satoshi and he doesn't outright say yes... To paraphrase, he basically answered, "I can't say for sure. It seemed like he (Len) lacked the C++ knowledge.. but his programming got a lot better since I last seen it... so I don't know. It seems to be the most likely scenario would be Len doing the brain work and someone like Hal doing the coding."
But, isn't that sorta what happened? Satoshi had 169 commits and Hal basically took over and cleaned everything up. Satoshi didn't do that much coding, and the coding he did do was done over 1.5-2 years (as he stated in the cypherpunk mailing list).
I believe Satoshi was a cypherpunk and a remailer dev. Cypherpunks had a history of doing things anonymously on the mailing list and even trying to out one another (a sort of game).
Furthermore, as a remailer dev Satoshi was all too familiar with what happened with the penent remailer[1]. He knew such services will become a legal target by the powers that be. This is why Satoshi even said we "kicked the hornets nest" when Wikileaks/Silkroad began accepting Bitcoin.
Meredith appears to be telling the truth. She didn't say Len wasn't Satoshi, she simply said to the best of her knowledge he wasn't. That doesn't mean he wasn't working on it covertly.
One of Len's best friends (Bram Cohen) knew Len was posting pseudonymously on the cypherpunk mailing list but never knew what handle he was using. Also, when Bram was about to release BitTorrent Len tried to convince him to do it anonymously. It's not hard to believe that Len would have done it secretly; even from his wife.
Furthermore, Meredith can't be 100% trusted. When Satoshi handed the project over to the maintainers and stopped posting to the cypherpunk mailing list in late 2010, Meredith tweeted, "Bitcoin isn't ready for prime time yet, according to its creator. Interested people can help finish it, though!"[1]
Satoshi never said those words publicly or privately-- so it's a curious thing to say.
As for the computer...
It's likely Len used university computer(s) for the development as the commit times and communication line up with an academic schedule. It's likely the university had Windows computers. Plus; it's one way to isolate the environment and reduce the chance of information leakage (could have even been a Windows VM).
That's why I hope the truth comes out. If say, Satoshi is Len, then Satoshi is no longer a god. He's a regular dude, that suffered like many people and tragically took his own life. There's a lot to unwrap there.
Fun fact, he was experimenting with email based image uploads on flickr. That was around the time Satoshi suggested they build an image hosting site that accepts Bitcoin.
It's not a leap to assume Len's brain made the following cypherpunk leaps:
remailer (anonymous email) -> image upload by email -> pay via semi-anonymous crypto currency
Len's own bio says, "I have a very strong interest in the real-world applicability of my work."
Len was a Macbook user, but he would not have done Bitcoin on his personal laptop. It's much more likely he used available PCs in a computer lab on the campus he studied/worked at, which were likely Windows machines.
It's also been shown Satoshi (and Len's) activities aligned and they overlapped with a school/academic year.
Satoshi stepped away from Bitcoin in 2010 and handed over the project to the maintainers.
Len started posting about Bitcoin in 2010 (post Satoshi handing the project over).
It seems to me, if Len was Satoshi, he grew distant from the project. Maybe it wasn't the cypherpunk utopia he envisioned. Maybe the wikileaks and silkroad issues weren't what he wanted to enable. Perhaps he wanted to distance himself further from the project.