1) people - everyone knows what FIRE is and more financially minded than an average person
2) profile questions - some are FIRE related and can matter greatly for FIRE folks, e.g. fat vs lean FIRE
3) design - no swiping, incentivizing talking to people today instead of waiting for a perfect match
In most dating apps these days (especially after Match Group bought most of them), you're shown one potential date after another and swipe across your phone to either indicate interest (say yes) or pass them by (rejecting them).
Typically I think you swipe left to ignore them or right to indicate interest. But it's been a while and I could be wrong about that.