Conversely, they fall with decreasing value of the company, and there are basically no limits. (historytools.org)
In fact, just driving a car off the lot after purchase decreases its value by an average of 11 %. (insurancebrokersgroup.com)
Also, if you won't have travel purchases you can redeem your miles for, you'll have to redeem for other options, which decreases the value of your miles by half. (mybanktracker.com)