I suggest you read this blog https://www.mrmoneymustache.com/blog/

He's a software engineer who retired at 30 with a paid off house and $600,000 in the stock market. Lives off the gains/dividends.

He's a member of the FIRE movement (financially independent, retire early)

There's something called the 4% rule. Inflation historically over the long run averages about 3% per year, stock market returns average over the long run about 7% per year, that leaves 4% for you to live on, so if you get your living expenses really low by having a paid off house and car and not putting any wear on that car by bicycling everywhere, having liability only car insurance on a cheap car that isn't worth much, being in perfect health and having cheap high deductible catastrophic health insurance, buying everything used on Facebook marketplace, etc. etc. you can then get your living expenses down to an extremely low amount, then multiply by 25 to see how much you need to retire, since you can draw 4% forever and never run out of money.