I'd imagine I'm pretty similar to grandparent post in this respect. If I find something interesting, I save it. Even if it's seemingly arbitrary or not immediately useful. With powerful search and tagging it's nice to run a query/update to a personal archive to refresh my memory, browse when bored, catalogue sources, wishfully think about future study, notice patterns in my interests over time, meta-analysis, etc.

More cynically, I've noticed that it's a relatively benign form of hoarding. i.e. I get the quick dopamine rush of "oh this is interesting, now I have it" without, say, crowding up my living space with trinkets. With an abundance of storage that is essentially invisible to me when I don't want to think about it, I can keep what I want, when I want; often while fully aware that I'll never look at most items individually again. I think of it as a kludgey form of external memory / internet butterfly collecting. The only downsides I've thought of are: time frittered revisiting archives, the (small) transaction cost of tagging and placing items into the archive, and the externalized costs of maintaining the hardware.