I agree with you, but we're talking about a device that I'd consider keeping for 10+ years. Actually I have some Synology NAS lost somewhere that I occasionally use, and while I don't trust exposing it to the internet (never have), it still serves files fine. With this expectation it's not absurd to get a NAS that still handles a bit more than the current speeds.

Just to add a datapoint: I could also get a 25Gpbs connection in Switzerland. Actually checking that, I'm realizing that I could upgrade without paying more (maybe just a setup fee, less than 50USD).

I'm also with Init7 :)