In my case I am on 1Gbps ingress/egress for ~43 EUR a month and could negotiate a deal for a datacenter level of a link (10Gbps) but I don't want to.
The reason I'll go for 10Gbps router and a 10Gbps switch is because if you put a NAS in your home network then the gigabit speeds will never be achieved again (various reasons, including LAN chatter). And also because I'll buy a 10Gbps-enabled machine and would like to be able to work with the data on my NAS with 1.25GB/s.
I agree that my planned setup is an overkill but I am setting myself up for such a tech overkill setup in all my work endeavours because I want to have a peace of mind for about 10 years -- if at all possible.
I don't think any of us will soon need more than 1.25GB/s ingress/egress anytime soon (unless of course our games are rendered on the cloud and streamed directly to our PCs). And since I am sick and tired of eternal tinkering, I want to go for an ultimate endgame, or at least one that can last me some years in the future.
Quite an investment I admit. But it's long-term. I don't anticipate changing that setup for like 10 years.
That's not the case almost anywhere though. And you won't be able to access your own stuff without internet either. That's would be very annoying for music, imo.