I am not going to beat you up about the merits of “free as in freedom” software. I don’t have any philosophical reasons to run Linux and it’s not a debate of ethics. For me, it’s all about trust.
The way I see it, I have to either fully trust something or be willing to accept a certain level of risk. Some risks are known and therefore easier to make an informed decision about, while others are unknown and therefore inhibit your ability to make risk-based decisions.
Risk is personal and very subjective. What is acceptable to one person may be an unacceptable risk for another person. For example, people cross streets because they want or need to be at the other side. To get to the other side of the street, they have to be willing to accept the risk of being hit by a car.
In my view, my computer is an extension of my home into the cyber domain. What I do in my home is my business. If I don’t trust you, I am not going to welcome you into my home.
However, I am willing to accept a certain amount of risk as long as the risk is known, such as having an Amazon Echo in my home or installing internet connected video cameras. These devices are acceptable because I am aware of their presence and I can arbitrarily remove one or all of the devices anytime I wish.
Proprietary software presents the risk of the unknown. It can include any number of risks that I am not aware of because my ability to audit the software is limited. And if I am not aware of the risk, I cannot make a risk-based decision about it. This is particularly true of operating systems.
For me, running a proprietary operating system is too much risk, but individal proprietary software packages are generally acceptable. This is because an operating system executes complete control over a computer, whereas individual software packages are limited in scope and I can remove them anytime I wish. With a proprietary operating system, you generally cannot move, remove, or change individual parts of it, so the only option is to not use it.
In summary, the primary reason I use Linux is so that I do not invite unknown risks into my home. I do not want someone else to exercise control over my information, restrict what I am able to do in my home, or collect “telemetry” data about my activities.