>Are these "market makers" working behind the scenes to facilitate the operation of those retail facing companies

Yes. Brokers like Fidelity have no idea how to price things, and even when they do, they don't know know how to manage the risk. Marker makers quote at the tightest prices they can offer and you trade against them, through your broker, on or off-exchange.

Market makers are often much more efficient and automated than brokers, but have similar or lower margins as a business and take a lot more risk. There's a misguided anger directed to electronic market makers, but it's in fact brokers that've been ripping you off all along.

> I don't do stock market trading

You probably do, indirectly through an agency agreement, for example a pension fund that manages your money. Or even whenever you just buy an ETF to invest. The costs you're indirectly paying are lower due to the newer generation of market makers that have reduced transaction costs for you.

> Is Black Rock buying all the real estate also good for (potential) retail investors like me?

Investing in real estate for years is not related to market making stocks with a holding period of 5 minutes.

I don't have a pension, or a 401k if that is what you are implying. I do have social security deducted from my paycheck. Is that money getting invested into the stock market on my behalf?

Sorry I'm not in the elite income class, I'm not directly familiar with the nuances of all these financial companies, or what they do. I understand risk. I understand lending money to pursue a risky venture. I understand time-value of money. I don't understand higher-order financial engineering except as presented in pop culture references such as wolf of wallstreet which I initially referenced, or the big short. I understand many machinations of society aren't directly visible as a "product" to the "average joe" of society but their ultimate benefit to society can usually be explained in a way I can understand, such as insurance, loans, industrial manufacturing, and such. These financial companies, as well as lobbyists, seem to just be skilled at manipulating a system and converting it into money.

Probably by your value system I am irrational, I don't chase money as an ends unto itself. I'm trying to understand Jane Street.

> I don't understand higher-order financial engineering except as presented in pop culture references such as wolf of wallstreet

The Wolf of Wall Street wasn't doing any sort of financial engineering in the real sense of the term. They were just committing fraud with pump and dump schemes. These guys had no actual quantitative or mathematical modeling abilities whatsoever that would be required for financial engineering and modeling. They were salesmen who swindled a lot of clueless people out of their money through illegal means.

You may not directly participate in capital markets but institutions around you that society relies on do. They do so to secure operating cash, loans, buy or sell insurance, etc. When people participate in capital markets they do so looking to make a profit or to purchase some utility, ideally these people have done some research about their trade before firing. Market makers compete for the right to charge you a fee (the spread) to make that transaction. You’re paying a fee to sell them risk (the risk that you’re correct with your opinion). Collectively this adds up to information exchange between all parties becoming less expensive: more participants on either side of any trade, smaller spreads, etc. Less friction. Options MMs are more or less directly buying and selling insurance.

While you yourself might not be directly involved with this, a lot of what makes capitalism go round ultimately goes back to these large institutions swapping vast sums of money around and market makers help facilitate a lot of that action.

Business loans, your savings account, your employer’s (or contractor’s if you’re freelance) line of credit, the global currency system, the prices of commodities that get turned into the physical products that we consume, etc.

Well, that’s the idea anyways. Whether or not the snake has consumed it’s own tail is a whole different discussion, but the stated value of stuff like this is to create efficient markets with correct price/price discovery aka make sure no one is paying too much or selling for too little.