The only justification I can think of for expensive knives is that they feel like more than just a cutting tool. Spyderco's, Benchmade's, ZT's.....these companies have the best craftsmanship and build, excellent reliability, some nice designs....but in the end they are just soulless, nameless cutting machines. I don't need to cut heavy duty items for a living, so I would be better off with a box of razor blades.
With expensive knives, I feel like they have a soul to them. Not just any expensive knife though, ones made by a master knifemaker, like Brian Tighe, Chris Reeve, etc. That way, I can take out the knife, and say "this man made and designed this by himself". Made with heart and skill, instead of computer generated numbers and skill. I only have one expensive knife, but the design and designer struck me as so extraordinary, and the interviews of the designer showed him to be such an awesome person, I had to have it. 3rd knife I had ever bought and already got my grail knife.
That's my take on it. Just my opinion, to each their own! Nobody can tell you what to enjoy