Futilitarian

 
A futilitarian is a person having the opinion that all human activity is futile.

Futilitarianism is a philosophical movement referring to the belief that all human activity (or endeavour) is futile.

She (the cat) reduced them all to tears of laughter, walking sedately round the room, then sudenly catching a glimpse of her own tail and tearing after it, with increasing frustration. "She's what the philosophers call a futilitarian. she recognises that what she's doing is pointless, but she does it all the same. It's a kind of ideological statement." - Adrian Mathews "The Apothecary's House"