> Persons B, C, and D are being paid a rate proportionate to the available labor market for their product building skill set.

The labor market doesn't set prices based on value to society and scarcity. If it did, nurses and teachers would be millionaires (there's a shortage of both and they provide high value to society) and middle managers would make very little (there's a glut and they provide very little value to society). It assigns value based on prestige. Capitalist labor market folks would argue strongly otherwise, but the evidence is very clear.

The law of supply and demand also doesn't explain or account for things like race/gender pay gaps, monopsonies, and collusion. And generally this doesn't pass the sniff test--if the labor market shifts and suddenly people in your profession are in higher demand, it's extremely rare that companies offer pay raises to keep their employees. That's because they know that while theoretically their employees can reenter the labor market to negotiate a higher salary with a different employer, in practice employment is very sticky and employees tend not to--for lots of rational reasons (some of which are "oh you're a job hopper, declined").

> There was nothing stopping persons B, C, or D from being person A and founding a company for that idea.

This is generally untrue. Companies build moats with patents, litigation, monopolistic business practices, and corrupt, ladder pulling litigation. I think a lot of committed capitalists believe the market will sort this out, but it clearly doesn't. How many upstart chip design houses are there? How many upstart medical device companies are there? Etc. Etc.

Furthermore and again, not everyone has the privilege required to be A. Being A takes more risk, and you have to have more resources to reasonably take that risk. It's also been shown that it's far harder for women, recent immigrants, and people of color to become As.

> Anybody can make a giant sized, billion dollar company.

What?

> Those workers chose to work as employees under standard labor terms.

Often people don't have the resources to start businesses (let alone billion dollar businesses). It requires a lot of privilege, and it's even harder for women and people of color. It's not at all a simple choice.

> The early Microsoft employees that made lots of money from their stock options probably aren't bitter about their compensation.

While being pretty tough to prove, I would say a couple things here:

- Microsoft continues to post multi-billion dollar profits, and people still work there. I don't understand why early employees are valued more than current employees here.

- It's conceivable that even if you made a few million dollars, you might be bitter if the person next to you who didn't work appreciably harder than you made a billion. Everyone's different but, that seems possible.

- Even if these effects are less pronounced or acceptable at a place like Microsoft, concentrations of wealth and capital have destabilizing, corrupting effects on society and governments. Taking a per-company view is short sighted. It's also worth saying that most companies aren't made up of relatively wealth software engineers, and income inequality will be more pronounced.