Other than being closed source kernel modules that taints the kernel and may cause black screen issues and more, do you trust it?
Also, it has a history with being broken on Wayland and they drop support for older GPUs which the Linux community cares about as you will find them more likely using older GPU as it just works than on being on Windows as it requires more resources.
Have open source Nouveau driver been serving you well?
It‘s I think not that relevant. Every proprietary driver is a security risk because you have to trust the developer to not code a backdoor into it Binary blob - Wikipedia if the driver isn‘t reverse-engineered publicly. If you are not accidentaly Richard M. Stallman (have you checked it? 
), it doesn‘t matter since your Computer is running already lots if proprietary things (kernel BLOBs, unfree JavaScript, boot process, Intel ME/AMD PSP).
Just try it, from a privacy, security and freedom perspective it doesn‘t make a big difference. If it‘s not working properly, you can still delete them, if necessary even with a live usb in the worst case it‘s not even booting
I mean.. my approach is if you need shit to work without this if it can’t, then you need to do what you gotta do. If not, it’s really upto you if you need it or not.
As a rule, I always stick with AMD or Intel when using Linux.
If you only need to have some windows display to see your browser, calculator and notepad you can probably do just fine with nouveau.
At the same time, if you have a dedicated external Nvidia GPU, I guess that you want to play or work with its raw power, in that situation your best bank for the buck way is to use the proprietary ones yes.
They might be glitchy and annoying, but fiddling around with the exact version number might fix it for you, YMMV. 
Some distros make it more or less daunting too, depending on how DIY and knowledgeable you are with Linux.
If you don’t trust the drivers, but you need to use your GPU, do you have any other choice? I have installed QubesOS on my gaming machine, which doesn’t have gpu drivers installed, so I could use that if I decide I don’t the drivers and use Bazzite for gaming only. I’m happy that my 2080ti is serving me well because I didn’t realize there’s limited support for Nvidia cards before I installed Linux.
there is now the nvidia-open drivers which does have the kernel part of the driver open source, so how is this still a question?
sure other parts are closed but if kernel is the concern, use that