Most audio gear does not hold value very well at all. Maybe if you sell quickly while a component is still in the "flavor of the month" status, you might do okay. Or maybe if the item becomes highly sought after or a rare classic over the years, it might actually increase in value. But for every one of those there are hundreds of other components which now sell for a fraction of their original price.
This is great for people buying 2nd hand, and not so great for those who purchased new. So it's a matter of perspective.