The proven strategy by most people that are wealthy today. Even the current top wealthies people, majority of their riches came from their investments.
I disagree with your statement because the top rich people today like Elon, Jeff Bezos, Mark Zuckerberg or Bernard Arnault...their wealth comes from founding and running businesses. They were already rich before investing in other assets like stocks, real estate or gold. Only Warren Buffett is considered one of the rich people through investing because most of his wealth was acquired through investing, he invested in stocks of various corporations from the early days of his career.
Financial investing is one way to get rich but not the best or only way.