I went nearly a year without a paying customer, even though I had an email list of over 300 people and a beta user pool of ~400 people, got on the front page of HN twice, and was #3 product of the day on PH. Still, nobody stuck around, much less offered me feedback. It was tough, and I considered giving up many times. But to call it a failure because of that would've been premature.
If your product isn't selling, maybe you're not doing something right (likely!), or maybe it's just not a good product. I think you can figure out which of the 2 your product is by putting some real effort into discovering why nobody is interested in giving you money for it.
The "why" may be your sources of traffic, it may be your messaging, it may be that your product doesn't actually solve a problem, or it may be any number of small things that build up and turn into a gigantic roadblock that nobody can pass without their hand being held.
I didn't start seeing "good" traffic until I started spending money to experiment with Google Adwords. Through that experimentation, I discovered that the traffic sources I was relying on so much were in reality total garbage. They were users from PH, HN and Reddit; "tire-kickers" as a lot of us call them. They just want to try out the hot new thing, then rinse (i.e. churn) and repeat with the new hotness. They aren't prepared, or willing, to open their wallet.
The Adwords traffic was actually converting, so I quit focusing on the bad traffic channels and starting adjusting my ads, finding better keywords, and talking to the "good" traffic (yeah, they actually talk back!). Since I was getting quality traffic now (albeit, low numbers), that helped me find the next roadblock, which was my, at the time, terrible onboarding flow.
The root problem wasn't that my product was bad, it was that I was sending bad traffic to my product and I didn't want to change that. The second problem was that onboarding sucked. I'm still not where I ultimately want to be with Keygen, but now I'm working on other problems (hint: scaling) because the root problems I was having have been fixed.
Stop guessing, and figure out the why.