The Bigness Bias
If you are haggling over the price of a box of fruit, you may be talking about just a few dollars, yet many people are willing to let thousands of dollars go when buying a house, being simply overwhelmed with the whole concept of hundreds of thousands of dollars. Other times someone may not think he has the money to spend $300 on a car stereo for his car, but if he buys a new car will spend several times that amount on a factory stereo system, as it is such a small part of the total purchase.
In an investment sense the bigness bias makes people ignore fees on managed funds, seeing them as a small part of the whole, even though they may have a huge impact on the compounding returns of your investment, or traders forget about the costs of such things as their real-time data feed or trading software, brokerage, bid-ask spread losses, and associated expenses, simply because the sums involved make them look small.