Because they’ve had limits on accounts combined with trivial registration of new accounts, combined with counting enterprise “accounts” from stuff like bing or api usage which really is just the same people using them over and over. That and startups tend to look at numbers that please them once and never question them. I don’t doubt they had a ton of accounts sign up. But MAU after 2 months isn’t a statistic it’s a data point, and coming from the most unreliable source possible.

Incredible growth in traffic is easy to explain - a lot of big companies and the most influential investors invested a ton of money in this. They have connections to all the top media sources. They pushed this stuff absolutely everywhere. It was a massive media blitz. You’re being manipulated. They’re hyping AI, they’re talking about doom and fear, they’re getting front pages everywhere. Everyone wants in - media wants in on the hype, social media users realize they can gain tons of viral views, it’s a giant pit of self reinforcing hype. That happens with things. See Pokémon Go, and then what happened a short while later. Or the crypto bubble. Or any number of bubbles. You can’t base your predictions of future success on self published popularity numbers after a huge and expensive media blitz.