Kindness is a variable state.

In a given community as our wealth goes up our level of empathy goes down.

In an experiment, in US a roulette wheel was control rigged so that a specific group will win twice as much as the rest.
As the game went on, few people became richer and richer than the others.
As the rich group moved from table to table, they became garrulous and started bragging about their dexterity, sleight of hand, power of predictions etc. None of them observed the unusual run of luck they had.
The other group started blaming their luck.

Then a volunteer was introduced who had been broke and asked for tokens to try his luck. The poorer group are twice as willing to share their earnings than the richer and unusually lucky group.

As our wealth goes up our level of empathy goes down.