When the researchers controlled for connections between socio-economic status and beverage preference, they found that wine-drinkers with the same financial resources and social standing as beer-drinkers or teetotallers simply lead more sensible and healthier lives.
Granted, Brooks does note a general preference for high-status mates, a keen sensitivity to evidence of our standing in the various social hierarchies we inhabit, and he does cite some empirical evidence to the effect that successful people tend to be self-deceived about their place in the social pecking order.