Much of the public discourse around economic opportunity is rooted in zero-sum thinking. Zero-sum thinking is a way of thinking about success in terms of "winners" vs "losers" or "gain" vs "loss" where someone else's success is at your expense. A common analogy is that when a pie is shared among more people, the slices available to each person get smaller. In reality, global economies and job markets are more complex than the distribution of dessert, and even the amount of pie available can be increased in response to greater demand...
By definition, zero-sum thinking positions you in opposition to other people. If you think that someone else's success inherently comes at your expense, you are likely to see someone else's success as a bad thing. If you think that your success inevitably comes as someone else's expense, you are more likely to adopt a defensive posture, trying to protect your gains from those who experienced loss.
When we think of it in these terms, we can see many of the ways that zero-sum thinking can limit our potential and deny us access to the rewards of connecting with others.
In a professional setting, if you it makes you look bad when someone on your team looks good, you are unlikely to help and support them. You might even undermine your teammate in an effort to "outshine" them. Not only does this prevent you from forming bonds with your teammates, it actually reduces the effectiveness of your team because it is being sabotaged from within. In a larger professional context, this can also make it more difficult to network and form professional connections that will benefit you in the future.
In a school setting, thinking of another student's good grade as being something that either reduces your grade itself or "cheapens" the value of your grade, you are unlikely to help them if they are struggling. This makes it harder to form friendships and get support from classmates when you yourself encounter challenges. Competitive attitudes towards classmates are further exacerbated in settings where students are ranked or graded on a curve.
In your personal life, this might lead to prioritizing "winning" over understanding during times of conflict, which can inhibit intimacy and produce lasting resentment. This way of thinking can even encourage an unhealthy quantifying of love where you think of a person as possessing a finite amount love, which means that any love given to someone else means less love available for for you.
In all of these examples, one of the most devastating long-term consequences is that forming meaningful connections with other people becomes harder when you see them all as potential threats to your success and wellbeing. If you can't connect, you can't build trust. If you can't build trust, you can't ever really let your guard down. That can be an exhausting and lonely way to live.
Burning bridges to limit the paths available to others also limits the paths available to you.
Aside from your academic performance, employers are increasingly looking for people who are skilled in collaboration. In some workplaces, an ability to see potential in others and support them as they cultivate that potential is considered an essential management skill, something necessary for promotion to a position that involves leading a team.
Even if you aren't interested in managing others, pretty much every professional path you could take in academia or industry would be smoother if you have developed the ability to communicate, connect, and collaborate with others. In the long run, your success will be intertwined with the success of the people you work with. Investing in the success of others helps to build loyalty and motivates others to invest in your success, producing better outcomes for everyone.