How many users does vaultwarden have? The docker hub shows over a hundred million downloads but only 1.4K starred. Any estimates? These forums are pretty quiet but that’s partly explained by vaultwarden being so stable there aren’t many problems to discuss. 
There’s no way to know how many installations are active.. and it’s a good thing.
Of course precise numbers are impossible. Surely the devs have an estimate in mind. Should the devs abandon this, a large user base is more likely to step in and continue the project.