Sadly, most of us are wrapped up in our own troubles and own worlds- it's true. I think that experiencing suffering or pain and having lots of free time tends to make us more thoughtful about all the other people in the same position.
To be honest though, as someone who works and has had very stressful and time consuming jobs, sometimes it can be hard to cope with anything more. It's like- maybe we can only handle so much stress in life. If all that stress is focussed on keeping ourselves afloat. Holding down a job, being financially independent, taking care of ourselves and our families- maybe a lot of people simply don't have the capability to cope with anymore.
That's not to say they shouldn't have compassion but- I kind of feel, if we tried to say do a complex job while worrying about climate change, all the children starving in the world, all the people suffering and in war zones- we'd just get overwhelmed. Maybe we hide in our jobs and distractions but for the vast majority of us- we have no choice but to work and to try to focus on the job to do it adequately. Then, after a full days shift- honestly, people want to indulge their need to feel happy. They likely don't want to be reminded of all the dreadful things going on in the world.
I also think there's a big difference between being aware of all the attrocities in the world and making practical steps to improve matters. People will say how terrible it is that animals suffer yet, they'll still eat them... And I'm not much better. I'm only vegetarian rather than vegan. People often only care to an extent till it means they will have to go without or put effort into taking action. Still, I agree with you. Sadly, it's a callous world out there unfortunately.