My wife of 24 years knows what my knives cost and she also knows how I care for them and of course my first love, which is guns.
Over the years she's seen me buy very expensive guns first and later knives.
If you care for them and they're not crappy stuff. You never really lose much on re-sale. I sell more guns to get others than knives. She's seen me turn a profit on many a fine double or a pistol that I just didn't care for. I kept them like new so that it was almost impossible to detect w/o a good field stripping that they were even fired.
I've adopted this strategy with knives: When I buy something new and kinda pricey like a Sebenza, an XM-18, XM-24. I don't even use the knife for awhile until I'm completely satisfied that there's no way I could sell it. Then I'll stick it in my pocket and cut some boxes arriving in the mail.
If I need to dump it, I break close to even and in some cases make a profit. I've put knives in my safe and fooled around with them for awhile before making up my mind. I had two fixed blades in my safe for 20 years and sold them both the minute I put them up for sale. It keeps me from accumulating a bunch of stuff I'll never use. I did that once and I had boxes of knives that I ended up selling off.
I was looking at my XM-24 (never carried or used - yet) today and told her that online dealers were getting over $1400 for "gen 3 production models" exactly like I had in my hand and maybe I should sell it for less than that and use the $$ for something else.
She said "and then you'll be miserable and wish you never would have sold it. I think you should just keep it." I love this woman.