How would you practically become a lord by buying public shares on a working class salary?

That's the trick, you won't. But they want you to think you can

YOU can do it, since you're here and presumably have a technical skill that can pay 2-5x the median income. That opens up the door to saving and investing your way to wealth MrMoneyMustache style

I agree that most people can't, and we need to do something to ward off a populist uprising

Ward off a populist uprising perhaps by actually fixing the system to work for everyone instead of the few with money?

Yeah, that's what I'm hoping for. I guess the other option is using technology to turn the entire country into a maximum security prison. We seem to be running full steam ahead into the prison future, though..

Yes you just need money so you can make money, why can't the poor just figure this out? ...

It's pretty good advice on a micro-level, though. When you see a situation brewing where one side is going to get screwed and another side is going to get-off handsomely, take the winning side of the trade if it's at all open to you. Do this enough times and you end up one of those rich capitalists, because each trade that ends up in your favor opens up more opportunities for future trades.

Yeah sure, be a part of the problem, that'll solve everything!

Now where does the average person find the initial capital, such that they can enter the game of capitalism..

Capitalism has a bunch of negative feedback loops - usually by becoming a problem you help solve it. If people notice that a particular good is about to become really expensive and switch sides to become a producer, they increase the supply of it and drive the price down. Even if they hoard and don't produce anything, they drive the price up early, when existing producers might still be able to increase production, and then drive the price down during the shortage as they unload their hoard. If people notice that renters are going to get fucked by rising rents and buy property to become landlords, they increase competition in the landlord market and drive rents down during the crisis.

The average person gets the initial capital to enter the game of capitalism by living like a poor person and banking the difference. That's how it works: this "capital" that earns a return is simply the difference between what people earn and what they consume. If you get a positive return on it you might eventually start being able to earn like a rich person and live like an average person.

This system will create at least three times as many Lords.

But that's not enough Lords!

Strong, "let them eat cake" energy with this one.