That's a great question. At a certain point... yes. But I think that number is much higher than a few hundred thousand users. If you think about departure cities X destination cities X available dates and times X number of seats, the number is huge. I'm not saying it won't happen, but I think we have a long ways to go before we reach that level.

Even if it caps out right where it is... they're retired after not too long

Yeah, if they're pulling $5/mo from each premium subscriber, that's... well, some pretty easy math. They could put a cap on the userbase if they wanted and still be pulling millions per month just off subscriptions, not even accounting for ad revenue.

Pretty crazy that they're pulling that much revenue without even using affiliate links.

On the other hand, does it matter how long the business lasts? It seemingly has minimal costs and is making bank.

While flight industry is booming, almost nothing matters - just keep telling people they can fly cheap. Dozens of aggregators are already doing this.