A. You are born into wealth
B. You inherit wealth
Most of us don't fall into either of those two things under an economic system that is designed to extract the most value from the people working in it, the profits of which bubble to the top and never trickle back down.
This is why things like overtime are such an easy sell. If the company can afford to pay overtime, then there's no reason they can't afford to raise their workers hourly wages so they make the same money at 40 hours or less that they would working 50/60 hours. I'm here to tell you first hand that there's no increase in productive output of the company as a whole when everyone is working overtime versus when everyone is on 40 hours. That's a myth that needs to be quashed, especially with production being increasingly automated. As someone who visits our automtive and aerospace factories across the US frequently, the amount of guys I see standing around looking at smartphones is astounding, but so long as the company can post higher valuations by making it look like they're flush with both work and cash by offering copious overtime, they're happy. Boss makes a dollar, I make a dime and all that.
Sorry, I forgot to address your part about investments. Those are another bit of snake oil sold to the middle class to sooth their financial woes. Fact is, unless you have a considerable amount of upfront capital, all you're doing is lending money for various fund managers to gamble with. They profit more than you do, even when you do see the marginal increases you might see.