It was very popular, no argument about it, especially among then youngsters. But "everybody" blows it of proportion way too much.

>ICQ was not some elite hacker thing

Sure, exactly IRC was that hacker thing.

ICQ and AIM. Later, whatever the first Google one was. Back when it looked like ICQ or AIM. I think it was a Google run jabber system?

This is type mismatch + incorrect assumptions. In 2001 ICQ went over 100 mln registered UINs. Which is not the same as "active users", it's all registrations from the inception (minus 10000 reserved). Losing UINs was a very common thing. Password recovery required email, which wasn't obligatory during registration, even if entered wasn't verified, back then few people knew what "password manager" is, and finally emails weren't particularly stable identity before gmail. But even if we would, for the sake of argument, assume the number as active users count, regular internet users by that time were numbered at more than half a billion. So even with absolutely unrealistically high estimation, ICQ share would be less than 20% of then internet population. And more realistic is probably 10-15%.

I signed up in 1997 and my UID was around 3.5 million. That's not a lot of people in the grand scheme of things