Several reasons.
I still like physical media.
Living in LA, there are quite a few brick and mortar stores selling used CD's. And since I love a lot of obscure, avant-garde, progressive music, browsing Amoeba's, Counterpoint's, CD Trader's used avant-garde classical section, or jazz section, I will often come across a CD by a composer or artist I am not familiar with, that looks intriguing. So, I will usually take a chance and buy it, and often come across something truly brilliant.
With streaming, I would have never have come across these sort of discoveries.
I subscribe to Qobuz, which I like a lot. But they don't have everything by a composer or artist I may like.
For example, I love a serial piece by composer, Ernst Krenek, called "Static and Ecstatic". Qobuz does not have it. I have a CD version recorded by the Cleveland Philharmonic, and an incredible vinyl recording by the LA Phil chamber orchestra.
I am also a huge fan of an avant-garde prog band called Univers Zero from Belgium. They have 11 releases between 1977 and 2023. Qobuz only has 4, Tidal also has only 4.
So, unless I have my CD and vinyl collection, I would be missing quite a few of my favorite recordings.