Maxing out Runescape Skills?

Food for thought. How many people do you know who are going to 200M mark in a skill? I know two. And they seem like nice people, definitely sane people :-)

But for me, there is something deeply unnatural, I'd even say alien, in such goals. This 200M mark seems so artificial and at the same time so "grindish", if you know what I mean. There is simply no way to get so much experience points by playing the game. One have to grind his/her way through. Even 99s with their 13M are usually products of grinding, but at least it is possible to get the capes and still be in playing mode. But 200M - no way.

What do you think?
If you are one of those people who go for 200M, what's driving you?