Wow that's some perseverance
I am soon in the fourth year of working on my project and finally starting to see some revenue but I am constantly asking myself if it's worth it.
Thanks, perseverance and patience were the only things going well for me. My key takeaway would definitely to give products at least 2-3 years before shutting them down. Most apps take a long time to get noticed and SEO works only after a year of effort.
Have you tried to collaborate with people with tangential skills, e.g. someone with excellent sales/marketing background or in a niche like real estate or law or whatever that has a ton of insights?
Even for Blanq, maybe you could find someone that has a strong need for link shortening for their business, whatever it is?