Based on their public data, they have 20,000+ paying users, and 1500 users paying for the family plan, which if all of the users are on the cheapest $5/month plan (which, many probably are on the $10/month plan like myself, as that gives you unlimited searches) would give them $100K+ each month.
Sounds pretty sustainable already to me, unless they have a really large team and/or really inefficient infrastructure, neither which seem true to me.
