Linux

Pretty much this. Linux users often forget that, when it comes to specifically operating systems, the vast, vast majority of people are used to what they know, and literally instinctively reject change of any kind.

Most people do not even know what an operating system /is/.

Any one who has ever worked in IT knows this, that the vast, vast majority of computer users are laughably technically incompetent, to the point that they usually get angry when you try to explain basic foundational concepts to them.

Then add on top of that decades of marketing that conditions most of the small minority of people who bother to attempt to learn anything about software and hardware into basically believing slogans, tag lines, and going gaga for tech that has some acronym or cute name, which they understand nothing about beyond the most surface level description.

Summing up, while it is possible to convince a person to switch to a new OS, it is maddeningly difficult at best nearly all the time. People basically demand a perfect product, even though they cannot even come close to beginning to describe what its features would be, and will instinctively assume they know more than actual tech experts all the time.

That being said, if you could run a business of basically buying or acquiring used laptops for cheap, refurbishing them with a stable linux OS, and then reselling them, you might be able to have a successful business, but the problem is that flashing OSs all day long is extremely, mind destroyingly boring and unfulfilling.