"pull up the ladder behind you"

Why is the tendency to "pull up the ladder behind you" so pervasive today? Why do we tend to deny others the same opportunity or advantage that we used to achieve success? What is it about the position we have attained or the path we took that compels us to prevent others from following the same path?

I ask these questions because of the recent statement credited to Kemi Badenoch, Leader of the Conservative Party in the United Kingdom, who was born in London to Nigerian parents and who is reported to have vowed that if she were to become prime minister she would ensure that legal immigrants would have to be UK residents for a minimum of 15 years before becoming eligible for citizenship. Currently, the wait time is six years. Badenoch, though born in the UK in 1980, grew up in Nigeria, returning to the UK at the age of 16. She has conceded to being "to all intents and purposes a first-generation immigrant." Need I make reference to Elon Musk and his boss in The White House, who have made immigration to the United States a case of passing the camel through the eye of a needle? One was born in Pretoria, South Africa, before moving to Canada and later to the US, where he blossomed into the world's richest man and is now a virtually untouchable oligarch, sharing power with an elected president. The other is the son, and grandson, of immigrants: German on his father's side, and Scottish on his mother's.

Are these people ever struck by the irony of labelling people "illegal"? Do they ever wonder what it feels like to have your dignity demeaned simply because you moved from one country to another? My basic question is: Why are we humans so incapable of recognising the sheer hypocrisy of our ways? Why do we, myself included, think that success is a zero-sum game? Why is it so difficult for us to understand that supporting another person's success will never dampen ours? Why do we believe that our success in life is necessarily defined by the difference between "us" and "them"?

Make no mistake, I understand the arguments that can be made about illegal immigration, border security and national sovereignty. I readily admit that those are legitimate concerns. But those arguments do not obviate the questions that can be legitimately raised about inherent human selfishness and callousness.