If only 1% of those supposedly 4 million users buy dent from an exchange and then send it to the app that's 40 000 buyers daily if they spend 50 bucks on average that's 2 000 000 daily volume just from them leave aside investors and traders. There's no such thing. Where are those 4 000 000 users developers claim to have? I don't see them.
If 10% of the users buy from an exchange that's $20 000 000 daily volume.