Some of us did. As a contractor, you certainly can earn a significant multiple of the hourly rate you would make as an employee in most companies. If you set up your own business and build your own stuff, then you have almost astronomical potential: the software development business has low barriers to entry, and the right idea can scale from a small team to serving thousands or millions of customers.
However, it's not as simple as that: you absolutely must have a broader set of skills to work effectively in these ways. There are many management and communication skills that you wouldn't need much working in a technical role as an employee that are quite simply essential to working independently, and more still if it's not just your own work to be organised but a whole team/company. Also, you are operating without the safety net that being an employee provides: you typically bear all of the risk if you're on a high-margin fixed-price contract that overruns by a year, or if you put your own money into starting a company and your idea just doesn't work out.
However, it's not as simple as that: you absolutely must have a broader set of skills to work effectively in these ways. There are many management and communication skills that you wouldn't need much working in a technical role as an employee that are quite simply essential to working independently, and more still if it's not just your own work to be organised but a whole team/company. Also, you are operating without the safety net that being an employee provides: you typically bear all of the risk if you're on a high-margin fixed-price contract that overruns by a year, or if you put your own money into starting a company and your idea just doesn't work out.