it's more convenient to stick closer to the other Vongola people/learn about them for his [s]nefarious plans[/s] totally normal plans.

Plus why stay at a hotel when Naoto's house is free?

But mostly it's an excuse because he's lonely and never had much in the way of friends or family.

"Vengeance doesn't talk very much, and when it does it's mostly 'RAWR, KILL YOUR ENEMIES, RAWR!"