Some great answers here which mostly say the same thing: revisit the customer development / validation part as it appears you may not have done this correctly or in the best possible way.

You know from the results you've got that growth and repeat usage is not occurring (let alone revenue) and while it's tempting to think "perhaps we haven't found the right marketing channel yet" or "if only we gave it a bit more time".. the most obvious answer is always "this is not something people really want".

What you really needed to hear in customer development was "one of the biggest issues I have in restaurants is that I always get confused about what to order and it's a big problem for me. I'd happily pay to use a service on my phone which would tell me what to eat based on my preferences"

What I think you might have got is:
"sounds like a neat idea - i'd give it a go".

which really translates into:
"it sounds a bit of fun and novel and I'd probably try it out once and then never bother again. It's not really a problem or issue I lose sleep over to be honest"...