as you get older, perhaps your priorities change -
 you get married, have kids, buy a house, etc. 
Don't know - I am still a couple shy of 30 so I 
guess I'll let you know in a few years!  

Also, you have to take other things into 
consideration. For example, I am a packrat who 
has saved several books, toys, and samples of 
writing from my childhood. Don't even ask what I 
still have from high school - it's 
embarrassing! ;)  I can't imagine getting rid of 
ALL my cels, even if I lost interest in 
collecting.