There’s a famous story for kids which I’m sure we all must have heard during our childhood numerous times; the story of Fox and the Grapes.
Summarizing the story, there’s a fox who sees a vineyard and tries extremely hard to get the grapes but fails coherently. At last he gives up but rather than saying he failed, he says, the grapes are anyway sour.
The human nature is very closely similar to the nature of the fox. When they think that they’re losing an argument they go on to being in subjects which are poles apart to the topic on what is debate has being going on.
Such people who argue just for the sake of it are illogical and utter cowards. Such people should really have sour grapes for their entire lives.