FWIW, I second your concerns about music disappearing from streaming services. It's happened to me. If there's an album I particularly cherish, I purchased it. I have a NAS already set up so storage isn't a problem, but you've gotten some good advice there.
Regarding the "justice" of streaming, like it or not, it's not going away. I'll say this: For every artist or group I particularly like and listen to regularly, there are, I would estimate, about two dozen I have at least sampled and often added to my favorites for repeat listening. These are artists who, twenty years ago, never would have gotten a dime from me. In addition, many of these chance encounters are indy artists or very small labels that never would have gotten even a hint of exposure under the old system of distribution.