There are many ways to become a millionaire. Just take the following:
Bogleheads (buy and hold Vanguard Mutual Funds, live frugally)
Money Mustache (earn above average income, live frugally, cut waste, adopt stoic philosophy)
Bigger Pockets (house hack, rent, flip, etc.)
Millionaire Fast Lane: own a business and aim for high income acceleration / sell business at a high multiple
Millionaire Next Door: Live frugally, save and invest, own a small business or choose the right vocation
Rich Dad, Poor Dad: Convert earned income into passive and portfolio income as quickly as possible, buy real estate, aim to be a Big Business owner and/or Investor
I like owning a small business for the income it generates and buying properties or equity syndication shares for income + appreciation + tax benefits. I try to incorporate the best information I can find to my personal situation and get out of my comfort zone at least occasionally.
Mike