Everybody had ICQ. You probably are too young to remember, but ICQ was as commonly used as Instagram today.
No it wasn't and it's not even close.
I never had ICQ because I was opposed to replacing open internet protocols with proprietary walled gardens governed by unaccountable private corporations imposing clickwrap contracts of adhesion on helpless users.
Definitely a regional thing. Where I grew up it was MSN Messenger all the way.
AOL instant messenger was bigger in USA, it was so big that AOL remained a major chat service even into the broadband years (though AIM clearly was under decline by that point)
My 90s and early 00s social circle was AIM, Yahoo Games, and Neopets.
Oh. Misunderstanding. I thought I was replying to a comment about IRC.
When ICQ was at its peak, users of any chat software were a rather thin layer of population. So "everybody" is more than exaggeration.