There’s a tension between (a) wanting to believe that people who disagree with us aren’t so smart or successful and (b) wanting to believe that our opponents are successful because of external factors such as wealth, social status, and rhetorical ability. Liberals as well as conservatives can be torn, I think, between (a) thinking of their political opponents as pitiful losers, and (b) resenting the other side for having all sorts of unearned advantages.

That is Andrew Gelman, recommended by TGGP.  Naturally die-hard disagreers presume their opponents are both stupid and witty/well-connected.