I collected a great many things over the years, and for me it was always the enjoyment of collecting that was important. I never cared if I made a profit on the stuff I collected, and I still don't. The fact is, I'm one of those folks that doesn't turn over a portion of my collection to finance future purchases. Early in my custom knife collecting days I sold a few of the knives I purchased, but have not sold one in the last three or four years.
I still purchase knives that I know will have a good chance of dropping in value, just because I like them. I purchase knives from new makers that don't have a proven track record, just because I like what I have seen from them. Though I ususally do think a little about the future resale value of the knives I add to my collection, if I were to start thinking of my collection as an investment, that would choke the enjoyment right out of knife collecting for me.
In the end it really doesn't matter though, because you aren't likely to see the knives from my collection, on the secondary market. I suppose that after I die they may well end up being sold. Hopefully the person selling them will be able to get a decent amount for them, but if not, at least I had fun. If treating your collection as an investment adds to your enjoyment, that's great. It most certainly wouldn't add anything to my enjoyment, and that's why I collect.
I will pay more for a current knife from a maker than for an older one, because it is my belief that the current one should be better made. If a maker has improved his/her knifemaking skills over the years, then I don't want one one his/her knives. Why would I want to pay the same money for a knife that was made five years ago, and almost certainly not made as well as one that the maker would make for me now, as I would for a current knife? It just doesn't make any sense to me, unless the knife has historical value. I don't collect knves for their historical importance, so that doesn't factor into my purchasing decision.
It is true that an object is only worth what someone is willing to pay for it. That is not BS. You can as whatever you want for a knife. In the end, if someone isn't willing to pay that price, then the knife is going back into storage. You can ask whatever you want, but someone has to be willing to to pay that price, or there isn't going to be a sale. If you purchase a knife for $1000.00, and that makers knives have not held up well in the secondary market, you can ask a thousand dollars for it if you want to, but it isn't going to sell, unless you find someone that doesn't have a clue that you can take advantage of.