We know that ~10k people access Union Events at least once. But a shocking amount of people can still be playing the game. Like, I wouldn't be surprised if there was 100k different people who play the game, just not stuff like Union Events. But only a fraction of them will be lured by the Jewel promise from the app.

That, combined with people also logging in with their alt accounts, means that I'm expecting about 20k people to do it. It could be only 1k as well, but I wouldn't get my hopes up. Time will tell.