There is only so much you as one person can produce in a day. Your time and mental energy are, in some sense, your most precious resource. You have a limited supply that you can use in a focused and uninterrupted way each day.
So the question becomes, what is the most effective way to spend your time and mental energy?
Think for a minute about a person carrying buckets of water for their crops. There is a direct correlation between how much they work and how much water they get. If they want more water, they have to carry more buckets.
Now compare this to someone who uses their time and energy to build a machine instead. This machine is “passive” in that it works whether it’s owner is there or not.
Obviously there is great leverage in having a machine such as this. It can work day and night while your time is preserved to build new machines or relax.
In the modern day of the knowledge worker, we no longer need to carry buckets of water with manual labor. But there is certainly the mental manual labor of a 9-to-5 job, copying and pasting in Excel, or whatever it is that you do. It really is no different in the sense that there is a direct correlation between your time and how much your earn. If you want to earn more, you need to put in more hours and continue working each week.
Now, if you are surrounded by people who carry mental buckets for a living, the idea of building a machine might sound pretty silly to them. I’m sure the first person who built a water wheel felt the same way. It is more difficult to build, costs money for wood and nails, and might not even work.
While you are messing around trying to get your machine working, your bucket carrying counterparts will probably get a lot more water carried in the short term. They might think you are pretty silly spending all your time and money on a machine that might not even work while they are getting consistent progress each and every day carrying buckets.
But at some point you’ll get your machine working, and it will start to match the output you were able to accomplish manually. Even if your machine is only producing the equivalent of what you could do manually, you still have a very significant advantage: your time and mental energy are still available.
Because they have been preserved, you can now go on to build a second machine, and another, and another. When you have 15 machines running simultaneously your output will be far greater than any one person could produce (or earn in a job).
This is the real key: preserve your most precious resource (your time and mental energy). Build systems and machines that work when you aren’t there. Avoid mental manual labor that require your time for output.
What are the best modern examples of these machines? Owning and investing in businesses, income generating real estate, some web businesses, etc. With these machines in place you can produce far more than any one individual could with manual labor, and get rich in the process.