tldr; class mobility has a muted standard deviation, likely on purpose.
There are tons of intentional and unintentional barriers for class mobility.
Here are the socially accepted ways that class mobility is rigged for developers specifically:
* A royalty-free tech culture. Since successful software is often exponential we don't get the meat of the value we create at a job. This could be compensated for with stock, but it's not because of the next point.
* Common stock/preferred stock. Employees get the worse of the two. Ask the Uber employees about this, where they had to pay income tax on an illiquid asset. Followed by a liquidation event that they could only participate in if they were accredited investor status.
* Accredited investor status. This states you must already be rich to make early stage investments. This is an important one because the best time to invest in a world-changing company is as soon as you can. As developers we've had to sit on the sidelines and watch investors get rich from obvious good ideas like github, airbnb, uber, sendgrid, facebook, etc while being told we can't put disposable income into the market because we didn't have enough of it. For instance, $1000 in facebook seed round today would be millions. Note that you can dedicate 2-4 years of your life for a very small portion of a different stock class. I fully expect the SEC to try to stop people investing in cryptocurrencies with the same scheme.
* Class-based social status. Your broke friends and family will come to you whenever there is a problem. They are more likely to be addicts and gamblers(statistically). If you help them and things go wrong and you stop helping them, they will hate you. If you refuse to help them you will feel like the worst person in the world. The 'crabs in a bucket' mentality op pointed out is real.
* Income tax. This is a hotly debated topic since often rich people are paid well. But for a poor person who is paid well one year, it's brutal. Not to mention your estimated taxes come from last years income, so if you have a bad year after a good one you will be forced to loan the government a ridiculous amount of money. Which you _might_ get back, eventually, at 0% apr. Don't try this the other way though, they can charge 5% apr a month plus fees.
* Capital gains tax. Often on assets which lack liquidity.
* Inflation. Having access to inflation is having access to variable taxes on the entire population of usd holders. The rich will have a majority of their money in assets.
* Game-able taxes. Taxes are completely context-dependent and no sane engineer would design it this way. The rich can afford people to play the games, which only makes sense at higher valuations.
* College. There are good things about going to college, but 2 years of "core curriculum", obscene costs, and unforgivable student debt are not part of them.
* Marriage. It's expensive. Having a family more so.
* Lack of identity theft protection. When this happens you get victim blamed and treated like a criminal. If you have money you can pay someone qualified to fix it, if not, good luck.
* Health insurance. If you want to start a company you better be okay with poor insurance since it's tied to your employer.
* Highly politicized culture. Society is willing to hurt people out who have controversial ideas that contradict the norm. These are often just working stiffs, not the decision makers. See James Damore.
* Fixed wages. Wages have not increased exponentially even though the power of individuals has.
Honestly I think almost all of it is intentional, like how the big tech companies colluded on engineer pay.
The system being rigged is why I believe in cryptocurrency in the long term. Sure there are scams and problems, but the alternative is to play an unfair game.