Willful stupidity is often easier and more profitable in the short run, but you just might be picking up pennies in front of a steamroller.

I think it's best to go out of your way to believe the truth, even though you won't always succeed. I'm very suspicious when tempted to do otherwise, it's usually for most unwise or unhealthy reasons. There are exceptions, but they're much rarer than we'd like to think.

I believe a 'simple' cost-benefit analysis is warranted on a case-by case basis. It is not some absolute, abstract decision. Clearly truth has a price. Sometimes the price is relatively high and other times it is lower. The reward will equally vary. Rationally speaking, truth will sometimes be worth the trouble, and sometimes not.