Until your streaming service gets sold, goes out of business, "pivots," decides you or your worldviews aren't trendy, thinks you're a hacker, screws up your billing, drops support for your device, or any of the hundreds of other reasons the music suddenly stops.
Yes, this happens once in a blue moon. I've bought one album because of this, and the content returned to Spotify within a few weeks of its departure.
It is still, for me, a cheaper and more flexible option despite licensing squabbles. It also gives me the opportunity to find new artists and give albums a few listens before deciding on whether or not they do it for me.
My views are USA-centric, perhaps licensing issues are more prevalent in other countries.
Why not both? Spotify is cheap. I spend a fair amount on vinyl and CD/SACD (SACD/CD for classical and the occasional jazz record, vinyl for everything else) and still keep a sub for spotify for work listening and being able to just check something out - although I guess YouTube can do that for free in most cases, and with electronic music, often the only streamable recording of a lot of records.
More and more phones are removing uSD card support. It's a losing battle.
I don't want the plastic, the physical storage requirements, etc, of a CD. With digital I don't "own" the music, sure, but I've definitely lost more music in my life from scratched discs, people not returning CDs than I ever will through Spotify.
I hear what you're saying, but the convenience of a vast and portable library is compelling.