I have been dual booting for years now, even though I almost exclusively use Linux. I’ve been in the situation where I fucked up configuration and left my Linux in a not-so-good state. In these circumstances it was nice to know that I still had access a functioning computer while I figured out how to repair Linux. Sure, you can use your smart phone for basic digital necessities, but that’s not something I’d want to be forced to do.

Another thing you might need Windows for is helping family and friends troubleshoot their shit. I don’t know if that applies to you.

If disk space is not very constrained, then I’d always recommend dual booting. Shrink the Windows partition(s) to the bare minimum (add some head room) if need be.

Something I’ve never done personally, but which may be scary, is flashing the BIOS via Linux. Most vendors assume Windows in their software.