They actually support their phones for years. You can even still get most parts of the Fairphone 2 which was released 8 years ago. New android versions are provided for a minimum of 5 years, often longer.
They also source their materials and labor as ethically as possible.
None of it is perfect of course, but considering the fucked up phone market, they're doing an amazing job.
For the same price, a Fair Phone is always going to be outdated. They can't scale as much as the big manufacturers can and they (are trying to) avoid slave labor etc.
It's simply not possible to be as cheap as the others who do everything to be as cheap as can be.