What everyone says is true... it's because there's a lot of money being poured into crypto (even during this bear market).

That said, it's like its own economy, so where the money flows, that's where the people go. Companies are pouring money into advertising, just like in other business fields, and to advertise their crypto, they pick bitcointalk since it's like one of the top crypto platforms.
They're using the signature space for a main mode of advertising... and so all the masses are signing up for these campaigns for $$$
BTCBTCBTCNow you've got the lazy bot spammers who want to sign up with 100 accounts to 100 differnet sig campaigns, and instead of posting like a normal human, they go around spamming generic, rewritten statements of the poster above...