I have boxes (LARGE boxes) of old models that my wife doesn't know about.
I keep them for spare parts or to customize/experiment on. I plan on trying to do some battle damaged or disassembled maintenance type settings with some of them. If the paint finish is the big problem with an old model's appearance, I use a product called Greased Lightning (biodegradeable degreaser) to strip the paint and give it another try.
Sometimes I give them to my son. He is just starting to build models, but he loves to play with them! So while he destroys the old ones, I work on the newer, better models.
Several 1/170 battloids have met disastrous deaths at the hands of a six year old and his gundams!