For me, the point is to get people to treat me how I want them to treat me.
I spent my youth trying to look older because it's tiresome being treated as if I'm a child when I'm an adult, people talking down to me, being dismissive of my opinions, not taking me seriously and having them be surprised when I speak with wisdom because they think I'm too young to have any at all. The way I presented myself had a huge impact on how I was perceived and how others treated me. As part of this I dyed my blond hair brown and was instantly taken more seriously by many than I had been before.
I then had a few negative life experiences close together in my 30s and virtually overnight the stress was showing on my face and I looked older than I was. By then my hair was back to its natural colour and with the addition of the first signs of grey. I switched to trying to look younger, including dying my greying hair back to its natural colour, because people were treating me as if I didn't matter, wasn't important, had no right to exist in the world and didn't deserve respect.
Now I'm in my 40s and having let my hair return to natural to see what I had, I didn't like the white side stripes by my face and darker back of my head, so it's brown again because that's the colour I felt like being. I've had compliments about how natural it looks, how it's warmed up my complexion and I can see with my own eyes it suits me and makes me look more polished and younger than the messy looking side stripes and two tone white/blond (it skipped going grey and went straight to white) hair I naturally have.
Nobody complimented my hair when I let the dye grow out and the white do its thing. I don't care about the root regrowth now, it's no worse than when I had blond roots coming through in my teens and early twenties. The roots are showing a little from 2 weeks post dye, I style my hair different to minimise the impact of that as the weeks go by and re-dye the roots every 3 months. Even with roots showing the overall effect is still that of someone with brown hair and it has a different impact on the appearance of clothes, makeup and skin tone than half blond half white hair.
It would be nice if people treated others with respect and kindness regardless of how they looked but that's not the world we live in. Dying my hair is part of accepting this world and working with it, not fighting against it. To all of you leaving your hair natural and demanding to be treated fairly regardless, I applaud you. It just isn't a fight I want to be part of personally right now.