Do you want to hear something closer to music than what your current digital source provides you? Then spend the money to get it. There is no clear argument for not seeking better source material other than "save your money." The object of our hobby, or obsession, has never been to save money, but always to obtain the best reproduction of sound events. High rez digital, maybe in either format but definitely in SACD, will get you closer to the original event than any other format. You can buy a mid-fi SACD player and improve any hi-end audio system. Will it last forever? Of course not. Will it grow to include every release ever made in every other format? No way. Will it make you a better person for listening to it? Maybe. Will it make your jaw drop and your eyes widen? Without a doubt.
Every advance in technology implies obsolescence of older systems and is often more expensive than what it replaces, especially early in the cycle. But frequently, there is a bigger payback for the bigger investment: better sound, more music.
How much dough did you blow on your last cable upgrade? That was just a refinement of the same old technology of drawing wire. High rez is still digital, but it really is closer to the original promise of digital than CD can ever be. For under a grand you can get a nice player and 20 SACD's. You will hear music reproduced more true to life than ever before.