I disagree with this. I occasionally listen to streaming, but would rather listen to my collection. Having your own music is also important if you are somewhere without an internet connection (a plane for example).
Just try out Spotify (or Apple Music, Amazon Music, Tidal etc). All of them have pretty generous free-trial policies. There are reasons why just about everybody under 40 has gone over to streaming instead of maintaining collections of CDs and mp3 -- you will only find out those reasons if you try it. If you're like me, once you go over to streaming, you'll never go back.
As long as your collection isn't made of concert bootlegs, probably 85-95% of it will be on the streaming service.
So just make a streaming playlist from the same songs as your current playlist. There may even be a way to do this in an automated way -- Google it. If you have mp3s that aren't on Spotify, you can add them as local files to your own playlists -- I know Spotify supports this but I haven't done it.
Then, once your songs are in a play it's just a single toggle to download the entire playlist to your phone.
I used to take a lot of music offline so I could listen on the road -- but then I gradually found out that LTE coverage (at least over AT&T) is good enough that Spotify works great in the car over the cell network. And it doesn't take much bandwidth -- I listen a lot in the car and rarely use more than 2 GB of bandwidth a month for streaming. Often navigation takes more bandwidth than Spotify.
And if you like to explore new music, one of the great advantages of streaming services is that they have various ways to introduce you to new stuff based on your playlists, your favorite artists. You can even make a new playlist based on a favorite album. It won't all be music that you like, but you may hear something you like that you've never heard before.
And yet another advantage is that a streaming app on your phone can usually be controlled by the phone's digital assistant. Once you get the hang of it, you can play your playists or artists or albums while you're driving using your voice. I can't tell you how handy that is.
The biggest thing is to choose your streaming service carefully based on the features you want. Use the free trials. Because once you convert over and learn how to use it, you won't want to repeat that process.
