Seriously, whatever you do, you need to spend the same amount of time promoting it, otherwise no one will notice. 50000 downloads is nothing in 5 years, it is 2.7 users a day. If you are in SanFrancisco you can get more than 3 downloads a day just going to the street and talking with strangers.
And they got 2.5M in their series A. https://index.co/company/AppDotNet?utm_source=thenextweb.com
Where were their budget for marketing? At least I would have expected 500k in marketing and 1$ per install, them we can talk about the users not liking the product or whatever.
UPDATE: you can keep downvoting (I would appreciate a feedback comment to explain the downvote) but it doesn't change the fact that marketing is more important than the product and they didn't spend on it
Well, you shouldn't judge me so fast. I have an MBA with marketing and I have been working on marketing for some time in my life. So I am aware what a marketing plan involves, and promotion is a small portion of it. I cannot suppose the founders knew all about marketing, but I would expect them to spend some money in promotion even if it not wise money.
Maybe you like this more. You have to do some marketing: define your product, know your users, define your goals, find the channels where your users are, target them, promote your product to those users in those channels, measure the results, analyze what happened and rinse and repeat. (that was also a small definition because marketing is still more)