> If you don't exist, who wrote this comment?
The hands. Driven by the chemical phenomena taking place in the brain given the information it had been fed previously. Both the hands and the brain and the memories are mine but not me. The same way my finger is (I won't be less me if I loose it, neither I will if I loose a memory of something, even of my name) and my car is. I am merely the observer of all these but ok, then where this me which "merely is" is then? Nowhere because whatever a thing within my body or personality I could point to is mine. Where will that me go when I die or when the universe collapses into a singularity and booms in a next big bang - nowhere, which is exactly where it is now. Because it doesn't exist.
This is a very rough simplification though (in fact the hands, the memories etc aren't even mine if everything else in the world isn't). I had to digest this for years and observe this, excuse me for some nonsense, from different angles inside the multi-dimensional space of pure non-verbal semantic experiences perception. This can be a long way to develop this ability and I am not sure many are ready to go this way. No, I'm not a heavy psychedelic abuser, nor a new-age loon, nor depressed, nor psychopathic, I am sober, enthusiastic, generally Okay, happy and compassionate and the realization of the above only made me even more of these and helped me through the hard times.
The first step is to observe it (a pure meaning without words) when you know exactly what you want to say but can't recall a proper word in any of the languages you speak.
If I were to seriously rationalize this I would say nobody writes the comment, it is an emergent structure resulting from a very complex fractal system. Whoever is not really into this but feels curious and wants an easy explanation watch the Dr. Sapolsky's lectures on emergence in his behavioral biology course on YouTube.