I think open source does tend to win, it just does it slowly - often when the big commercial name screws up or changes ownership.
ex - I think Adobe is in the middle of this swing now, Blender is eating marketshare, and Krita is pretty incredible.
Unity is also struggling (I've seen a LOT of folks moving to Godot, or going back to unreal [which is not open, but is source-available - because having access matters]).
CAD hasn't quite tipped yet - but Freecad is getting better constantly. I used to default to Fusion360 and Solidworks, but I haven't had to break those out for personal use in the last 5 years or so (CNC/3d printing needs). It's not ready for professional use yet, but it now feels like how blender felt in 2010 - usable, if not quite up to par.
Office work... is a tough one - to date, Excel still remains king for the folks who actually need Excel. Everything else has moved to free (although not necessarily open source) editors. None of my employers have provided word/powerpoint for more than a decade now - and I haven't missed not having them.
I would argue that PDFs have gone the opensource route though, and that used to be a big name in office work (again - Adobe screwed up).
I don't really do any music production or video editing, so I can't really comment other than to say that ffmpeg is eating the world for commercial solutions under the hood, and it is solidly open. And on the streaming side of "Video" OBS studio is basically the only real player I'm aware of.
So... I don't really think it's wishful thinking. I think opensource is genuinely better most times, it just plays the long and slow game to getting there.