Bitcoin price is now high compare to its price in the previous years, it almost triple. So there is a high possibility that next year or after 10 years its price will also increase more and more. If the people hold and collect bitcoin until that day comes that its price increase, it will be a very big profit. That is the right time to cash out the money, and then collect another bitcoin and wait again for the price to increase.
Lots of money can be made day trading Bitcoin, but the easiest way to earn is by holding. No one who bought Bitcoin and held has ever lost money... think about that. As long as you hold for a couple years, you are guaranteed to get a return on your investment comparable to the stock market, and eventually there will be an exponential rise and your money will double/triple.