You are over evaluating the number of active users per month. Maximum was reached on 2017-07-18 and is 22k (22445 to be precise).
You can check on my daily stats to have a clear view on the evolution of active users.
That said, having fewer active users only reinforces what you mention about the value of Steemit.
RE: The value of Steem and its users: 1 Steem user = 10 Facebook users!