Most Americans with a net worth of one million dollars or more are self made millionaires, and they are passive investors, meaning they invest in total market, stock and bond index funds and forget about it.
They do re-balance their portfolio maybe once a year to make sure their percentages stay on target, but they don't watch the market, they don't buy and sell stocks like maniacs, and they don't worry about the market's ups and downs.
When you buy and sell stocks, you pay a premium in fees. Add taxes and inflation to this list of things that eat up your gains and you may break even at best, if you are trading stocks all the time.
Invest at least 15% of your salary in total market, stock and bond index funds and forget about it. You'll be glad when you're old enough to retire, and you won't spend your entire life worrying about this stuff.