If you don't attempt to "end racism" what would you have done about slavery? Or is racism - or any kind of prejudice - to be accepted or tolerated if it isn't so big or obvious? I'm betting there are certain words - racial epithets - that you would feel it unlikely you could get away with in public now.
To say it is impossible to "end" something sounds like an excuse not to try or to make progress - it's all too hard. I don't think MLK Jnr took that view. Or anyone who strove to make the world a better place.