So I’m curious, is this simply normal human competition or does it become unfairly holding others back?
To me, this is as a result of personal difference, some people are naturally greedy because they don't want people to do what they are Also doing. As in when they are benefiting from something they just want to only be the benefactor, but provided it involved other people they act cold or negatively. Some people don't mind everyone doing it, but if the opportunity is limited and involving many people will reduce their chance of taking big shear, they discourage others from taking further step.
Apart from that, human always have that mentality that too Many people involving in particular project reduce the chances of benefiting from it.
You're right that greed has a lot to do with such behaviour, but there is more to it. Some people are just generally evil, they don't want others to succeed or reach their level or go higher than them, because such people believe they should be superior to everyone else. It's a very wrong mindset to have, and there are a lot of examples of such people actually losing everything eventually, because as wise people said, what goes around comes around, which means that if you do good to other people, your good deeds will come back to you sometime in the future, and the same goes for bad deeds as well.
People who become happy when they see others succeeding in their lives or careers, and they would never hesitate in sharing whatever knowledge or information they have about something they are into. This also reflects in a person's character in the long run, which means that you can pretend to be good when you are not but only for the short run, in the long run, your real face will be revealed, and when that happens, you won't have anyone standing beside you even if you have hardships because you didn't do anything good for others when you were in your prime.