Thousands of years ago, if you were in a hunter-gatherer society, you may want to share. It’s valuable because when hunting, there is always a bit of luck involved in landing your next meal. Each and every time you hunted required luck to come across the animal you were looking for, make sure that they didn’t sniff you out, and then make sure you are able to get the right shot in. If you can share when you bag a big animal while others came back with nothing, then perhaps they would do the same for you in the future. This would eliminate much of the ups-and-downs of each individual’s success.
At the same time, if you were a farmer, provided you put in the effort to plant the seeds and reap the harvest, barring a bit of bad luck, you had food. Sharing with others who weren’t willing to put in the effort may have been frowned upon because they could have worked too and had a steady harvest. It wasn’t bad luck. It was their effort that was the issue.
In this same vein, there are people with many friends and family to lean on, and people with few.
There are people in modern industries that are cyclical, and people in industries that are rock steady.
There are people in positions where failing leads to no further chances, and there are people in positions where there is always another chance.
The sum of these types of situations form our worldview. Just because someone believes a bit different than us, doesn’t always make them a bad person. They just have a different situations forming their world-views.