Yes, I have my entire music collection on Google Play. It took days to upload it all, and I’m still working on fixing up the metadata (Google doesn’t support some of the tags I had on my files), but I feel better knowing it’s there.
I got rid of my LPs years ago (after making digital transfers of the ones I wanted to keep), and although I still have all my CDs, I haven’t touched them in ages and haven’t bought a physical CD in years. After experiencing a couple of hard drive crashes and seeing how unexpectedly they can happen, I’m not about to depend on them.
If I’m somewhere that doesn’t have wifi I’m listening from offline files, but anywhere else (like at home) it’s just Google.