There's tons of businesses that "print money" as one or two man LLCs but they don't scale well beyond that point. There's several overhead jumps as your company grows to a point where you have to pay someone else to do something because you can no longer do it yourself (hiring your first few employees, company gets so big you need to get someone to do HR/payroll stuff, company owns so much stuff you need to hire someone to specifically maintain the equipment, etc, etc). Sure you can scale but then some other smaller business with lower margins comes along and out-competes you. For businesses where the cost of entry is low this happens fast.

It also is worth mentioning that owning a small business is not nearly as good of a work/life balance as being an employee. Expect to work 40hr week managing the business directly and then another 20-40 doing all the behind the scenes stuff that the business needs in order to run. Obviously conditions vary a lot based on what you do and the local economy.