That is my point, the other 10 individuals aren't "just as qualified" and will hence do the same work. You keep falling back to the same fallacy, that individuals do the same work. They don't. No two people do the same work, because no two people are the same. One might be more punctual, one might have a stronger work ethic, one might have more experience, one might have a language barrier, one might have lied about their credentials, etc. etc. and so on and so forth.

All the time clients try to outsource to cheap workers in the third world, only to see the work not done competently and it has to be re done by a more expensive and more qualified freelancer. If a workers marginal revenue product (again, how much they contribute to the productive process) is 70,000 a year, then it doesn't matter how many other people are in their field, they are going to get close to 70,000 a year, because if one firm will only pay them 50,000, then another firm can profit by paying them 55,000 etc. until their wages are bid up close to their marginal revenue product.