Meta doesn’t make money if you buy its hardware used on eBay or similar
Walking around wearing Meta’s hardware supports them by you advertising their product (unless you never show anyone that you own the hardware).
The existence of a used market also slightly increases the value of new things. By buying used, you’re supporting/signaling the used market and indirectly supporting the company.
If you don’t want to support a company, don’t go near their products.
I'd have to be pretty sure I could use the hardware forever without a login for me to let it near my systems. Anything with firmware or a security footprint would not qualify.
I might accept a Meta paperclip into my house, but then again, why risk it ;)
Meta's game is to do all sorts of dirty tricks to pull you into its data. No thanks.