But investing in the stock market is one of the most effective ways to increase your net worth -- and even become a millionaire. Image source: Getty Images. S&P 500 ETFs are relatively safe ...

See the 10 stocks » That makes an S&P 500 index fund like the ... However, investing $25,000 and adding $500 monthly would still make you a millionaire in 30 years. If the index does achieve ...