As someone who spent most of my life with short hair but only started growing it longer in the past few years, I suspect that a lot of people who haven't had long hair drastically underestimate how much work goes into keeping it healthy and neat.

Nah, just stop shaving as well and people compliment you on the commitment to the beard. Added bonus for the Unabomber vibe.

More importantly, if somebody wants to pay a hairdresser, what business is it of anybody else whether they "need" it or not?

I'm saying I don't agree with it! (and I say that despite not having had my hair cut since the pandemic)

Need vs desire. A buzzcut, which is easy to give yourself, is all you need. Of course, it is understandable why you might desire a different style that is beyond your own capabilities.

All jobs fulfill something desirable for someone, but they aren't necessarily needed.

My mom was the first in her family to pay for haircuts. Before that either your mom did your hair, or your mom's friend came over and did hers. I didn't get a paid haircut until junior high. So people don't need them in the way they don't need automatic dishwashing machines to have clean dishes.