They've delegated, automated, streamlined, systematized, etc. Not with the intention of sitting on some beach somewhere for the rest of their lives and watching the checks roll in, but with the intention of freeing up their time to create even more value that they're inspired to create, either by leading that business to the next level of greatness and service to greater audiences, or by starting a new business.
Venture debt ($12,240 a year): The first venture-debt fund has returned almost all my initial capital, so I decided to invest $200,000 in the second fund. I took a risk investing $150,000 in my friend's first fund, so I'm hoping there's less risk in the second fund, given he has four more years of experience on top of his 12-plus years of experience running a venture-debt portfolio for another company.
If you have specialized knowledge in a certain topic, you can put together an online course to teach others. For example, if you have experience in real estate investing, you can create an online course “Real Estate Investing 101”. The benefit of an online course is that once you create the course material, you can sell it to as many people as you want.