Investing isn't just "doing nothing". You have to chose well and know what will take off and what won't.
Speculation is trying to pick the right horse. Investment can be just as much about trying to create a balanced portfolio that'll get you a reliable return. You tend to hear all about the spectacular successes and failures, but a vast number of companies produce the nuts and bolts, everyday objects that don't change much at all - not the production systems, not the demand, not the competition. But somebody owns it and somebody's getting a return on it. It's not very exciting to hear that they got 5% ROI while the stock market index 4% ROI though, so you don't read about it much.
What really matters is the value of labor vs capital, once we had artisans and master craftsmen whose work was highly valued. Then we had industrialization and it trended more towards capital, then it trended more towards knowledge workers and now with automation it's trending more towards capital again. If the rich accumulate wealth quicker through capital than people do through labor then the gap widens. The winner is the ones who can invest a billion in self-driving cars, the loser all the people who used to earn a living driving.
Sure, some people will gamble and bet on the right horse or the wrong horse and either join the capitalists or flunk out back to the working class. But they're just statistical noise when it comes to the rest question, how much of the wealth does the 0,1%, 1%, 10% control? It excludes the whole issue about who left and who joined, only how unequal wealth is distributed. And last I heard the differences were increasing, the rich are accelerating away. They don't have to be super good at investing, they just need to not be super dumb.