Note: This post may be edited in the future to add more detail and accuracy.
1. ‘Itachi needed the WiFi Connection’ Theory
Yup, he killed the entire clan in order to get that coveted wifi connection. Konoha apparently cut off the Uchiha’s wifi access after confining them to the outskirts of the village. So they had to establish their own.
But the internet service provider was crap.
Itachi killed them too. He figured there were better options… out there… beyond the horizon…
2. ‘To Make Sasuke Stronger’ Theory
Yes… It was a brilliant plan. Completely foolproof. Why didn’t anyone think of it before? It was absolutely genius.
Best way to ensure that your kid brother grows up to be a strong, powerful, reliable psychopath, traumatize and scar him for life.
Parents, forget all the advice those child psychologists tell you. THIS is the guru of childrearing right here. Uchiha Itachi.
3. Sasuke-Committed-the-Worst-Crime-Known-To-Humankind -So-Itachi-Killed-The-Clan Theory
Itachi’s Dinosaurs are like what Good Thought-Nuggets are to me.
They are worth your family, your friends, your clean record, your dignity, and your sanity.
They say that Uchiha Sharingan eyes can still be exchanged in the black market for Itachi’s dinosaur.
4. Itachi is a Violent Incel Theory
Hard Core Itachi fanboys believe that Itachi’s killing of his crush by giving her a dream life in less than a second was a mercy killing. Because of course, the mass murderer is perfect. Because of course, Itachi fanboys are all potential incel mass murderers in the future.
So I, ShawarmaHead believe it is VERY possible that Itachi was an Incel himself. And like ALL incel psychopaths, romanticized his crimes against humanity.
The Elliott Rodger of Anime Ladies and Gentleman.