“Dollars and Sense,” by behavioral economist Dan Ariely and Jeff Kreisler explains that people tend to approach money irrationally. But to build wealth, we have to out-think our emotions. To do it, we have to be aware of psychological pitfalls like “opportunity costs” and the “endowment effect.” Saving money is notoriously harder than it seems. Things pop up — car repairs, wedding gifts, invitations to concerts — and suddenly our good intentions go straight out the window.  So if you’re trying to save more and spend less, you’d do well to stop telling yourself how important it is for your future […]