Not just really cared, but didn't even care at all.
Would everyone be selfish? Would more people be murdered? Would there be more suicides?
Yes...because no one would care. No one would care for their life, for their families. Maybe they wouldn't even want families in the first place.
Would anyone even want to be with the person they loved? Would they even love at all?
No, because no one would care.
The world would be a hopeless place, filled with a hopeless people. People who let their children starve, if they even have any. A people who would never progress, because no one would care enough to challenge rules. If there would be any rules at all. The world would contain a people that always shrug their shoulders if they were asked a question, or roll their eyes at miracles. Pass by a person dying on the streets without even a glance. They wouldn't want to help anyone, but expect everyone else to do what they would want. But it would never happen.
And the world would fall, because no one would care.