Explain to me why you would hire somebody if they lose you money.

Value is subjective, you can't point to x worker and calculate exactly how much "value they create" to the company, because many things a company does are not possible or nearly impossible by individuals. If you calculated how much value each employee brings in by subtracting what the company would have made in their absence, that would often result in being more than the company makes for most high skilled jobs.

That's why I said worth not value. You can define what a person thinks they are worth by asking them.

Please provide just one example.