That is because most people are not consciously attempting to become better people for the betterment of those around them (which helps their own happiness, too, due to the nature of our karmic universe). Most people are simply acting out of the selfishness to have their own desires fulfilled, with varying amounts of concern for the consequences to those around them.
A person can undertake self-evolution in any direction they choose; it is always our choice, except in the extremely rare cases where a person is physically damaged. Most people have the power to change, though it is difficult for us all. The universe does help those of us who seek to do so for the benefit of others.
What makes human beings unique is that we have both the ability to self-evolve our attitudes and behaviors, and the tools to do so, our mind and conscience.
>> Personality Capture
A person who is not undergoing conscious-self-evolution is susceptible to being influenced (and even overwhelmed) by a forceful personality that caters to their desire-seeking. That is how dictators have always risen to power: they seek a loyal army of folks enamored with the leader's promises to make the in-group's lives better. Those folks never seek to make life better for ALL people, because helping out-group members requires generosity, which usually requires making some level of selfless sacrifices of resources.
As always, the strife is between selfish callousness and selfless care. Compassion for all our fellow human beings is the nature of being a humanitarian, that is to say: being the best of what we can be, for the benefit of the entire human race. And it all starts with each and every one of us.