This highly depends on: Is this a one time thing? and How often would you fly first class?
Many people would probably say that spending the money on a first class ticket is a waste of money and part of me thinks that way too. But when you take into consideration the number of times you are travelling with such ticket, it's actually not that much.
For reference: if you have 1MIllion USD and you only plan to fly once on a first class plane. Then for only $5000+ you gain the experience and the lifelong memory of having flown at least once on such an expensive ride. You can brag forever to your friends that at some point in your life you have done this feat. Flying once isn't that a big deal and is actually very rewarding.
However, same can not be said for flying on an expensive plane 3-5 times a year. Those $5000+ easily accumulates and will tank your imaginary 1Million USD.