Attractiveness is not a one-dimensional scale, it is a two-party phenomena.

The zero-sum here depends on who is who. The competition is zero-sum, but the relationship is not.

If the market is to exchange affection, it's positive-sum. If the market is a status good, it's zero-sum.

The most effective person gets hired into a role. The firm performs well, moves more product, lowers prices for customers, sends larger orders to its suppliers, invests some surplus in R&D, grows its payroll, generates return for shareholders who then invest their gains in other enterprises, etc. Or an ineffective person is hired and the opposite happens.

https://en.m.wikipedia.org/wiki/Lump_of_labour_fallacy

If you had two job offers, one salaried at $100,000 and one at $100,001, I assume you would pick $100,001 with zero consideration for any other factors?

It assumes there is only one fixed org chart and role. This isn’t true everywhere under all circumstances, but my personal experience in tech has been that companies make space for talented people who have a real impact. If you’re fighting over a title, you’ll stagnate. If you’re growing the business and building useful things roles will invent themselves. Especially in the case of competing with an individual over a role, making each other look good is far more valuable than being competitors.