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<p>Not merely passionate, but also good at what you do and able to find a market for what you do that is either un(der)served or where you can outcompete the incumbent suppliers, if you want to become rich by earning a high income. Perhaps some luck also helps (e.g. choosing the stock/options-offering startup that becomes successful, rather than the one that goes out of business).</p>
<p>Of course, to retain wealth, you also have to avoid spending all of your income as fast as you make it. The Millionaire Next Door book describes people who accumulate wealth “under the radar” by frugal spending habits (even though some do not have high incomes). In contrast, the flashiest people may be financing the flash with debt.</p>