I generally use them eventually although I may drag my feet about using them for a while. It boils down to whether I need to use it and I suppose want to use it.
Most knives are not good investments. Customs/handmade?..... well they may be more valuable to you, but even if the maker dies, chances are that within a short time, nobody will remember their great knives. There are of course exceptions but the reality is that you have to be willing to sell it and the value means little if you aren't willing to sell. That is sort of my problem and has been. I finally started selling off my Colt collection slowly. Some of these guns I have owned for more than 30 years. I don't own any knives that I would consider investment worthy. So, if that's you, use it and enjoy the knife, or tuck it away for a while.