For me personally it’s because looking at human history we haven’t really changed when it comes to humanity itself. All we’ve done is increase our ability to procreate and harvest resources.
We’re still the same selfish violent monkeys we were 150,000+ years ago. Now we just have shiny toys to kill things with instead of rocks.
It’s more than a few is the problem. In fact it’s heavily skewed in the favor of bad apples. There are more half rotted apples than there are pure clean apples.
It’s in our instincts to be selfish outside of small populations.