PERFORMANCE COMES AND GOES, BUT COSTS ROLL ON FOREVER. - Jack Bogle. Controlling management costs in your investment may make the difference in a nice profit or a loss when you dispose of the investment. The profitable investor is the one that manages cost over the hold period so that those lofty sale values we project at acquisition may come true at dispositon. Buy low, sell high is only part of the story. Watch costs as closely as you watch (project) appreciation.