Free & Open Source software benefits everyone, which sadly includes bad actors and companies you (and maybe I!) don't like. But don't forget about the "everyone" part, which is the most important one!
But in my opinion, any software being FOSS is benefitial, even if you cannot deploy it yourself for your toy projects. If anything, you get to play with it or learn from its source. Maybe parts of it are useful to you for your own project. You cannot do this easily (if at all) with closed proprietary software.
Good software benefits everyone.
Whether it's open source or not is irrelevant.
It is definitely not irrelevant whether software is FOSS or not. It's the whole point of the GNU project, the FSF and of the Free and Open Source software movements. I'm not going to write a manifesto about the reasons here, but surely you must be aware a lot has been written about this in the last few decades that cannot be dismissed with a flippant "it's irrelevant".