It is correct that your employer has a certain amount of power over you; so far, so good. However, note that even the largest employer in the world won't even employ 1% of the workforce so the power of a single employer is really small, and if the employer tried to use this to order their employees around, they would have a massive PR-problem.You fundamentally misunderstand the concept of "wealth"[...]Wealth isn't just the ability to accumulate material goods, it's also the ability to attract labour. Wealth hires, and also fires... which provides a significant amount of leverage on those being hired/fired. So long as the distribution of wealth is fairly wide there are countervailing forces and no individual employer can get too rambunctious (ie: labour leaves the pointy-haired tyrants for better bosses elsewhere).
The reason some people are paid high wages while other are paid low wages has absolutely nothing to do with the niceness of their employer. It has to do with supply, demand and productivity. The fact of the matter is that if an employer pays 20$/hour for someone who produces wealth at a rate of 50$/hour, his competitor will eventually pay the man 21$/hour to come work at his place. Then the original employer will offer 22$ etc. etc. That's why a free market doesn't have permanently underpaid jobs.But if wealth concentrates into a few potential sources of employment there are fewer potential exit vectors for dissatisfied labour and thus fewer reasons for employers to "play nice". Wages go down, working conditions get worse, wealth concentrates even further into fewer hands.
Yeah, that is the left-wing theory, and since Marx predicted it it has never actually happened anywhere except with the help of the state. One of the reasons for this is that there is an optimal size for every company; when it becomes larger than that size, the costs of administration grows faster than the advantages of mass production. Another is that people make mistakes. And when a company gets larger, the mistakes becomes costlier.The end result is a collapse of a market economy because there's not enough competition... and because the concentration of wealth is high enough, there's no incentive for those with wealth to capitalise possible future competitors.
This can be proven by the fact that every sector of the economy has plenty of competitors. While monopolists have existed they have only ever occured with the help of the state and/or in very young markets.
I know what happened to the Weimar republic. But the causes of it has nothing to do with what you just described. (And btw, the reason why the German economy was cartelized was regulation; it was a willed policy by the state prior to WWI(and possibly after).)All of that, without once invoking force of arms. That happened in Rome, and the Republic eventually turned into an Empire to cope. That happened in Weimar Germany in the 1930s, and we all know what happened to them.
Regarding Rome you really have to fill me in; what did the fall of the republic have to do with the alleged monopolistic tendencies of capitalism?