I'm a plant lover and it's hard for me to throw out a plant -- especially a houseplant. I tend to keep them around for years. Like the Christmas cactus in my office that my son brought home from first grade...back in 1994. But I feel differently about amaryllis.
Storing amaryllis bulbs from one year to the next is a bother and you can't always count on getting flowers. With a freshly-purchased amaryllis bulb, I know I'll get great results every time. So I treat amaryllis like I do fresh flowers. Once a bulb has finished blooming, I simply throw it out.