10 GbE cards and adapters are still quite expensive (at least compared to cheap $10-20 1 Gbps gear); one of the cheapest ASUS 10G PCIe cards is $99, and the cheapest Thunderbolt 3 10G adapter (both with RJ45 connections) is $149.
If you want to graduate to SFP+ those adapters usually cost a little more (plus the cost of a transceiver for fiber or copper).
Cabling also means many existing installations (like my house) with 50+ ft runs need to be re-cabled if they actually want stable 10G speeds. My home network works great at 2.5G but there are a few Cat5e runs that don't give me 10 Gbps.
The reason why I want to have 10 GE is that I made sure that the cables in my house could support these speeds. I expect more and more devices to support 10 GE as I will install them in the future (new TV, new workstation). This is just future proofing of my network installation.
If you want to graduate to SFP+ those adapters usually cost a little more (plus the cost of a transceiver for fiber or copper).
Cabling also means many existing installations (like my house) with 50+ ft runs need to be re-cabled if they actually want stable 10G speeds. My home network works great at 2.5G but there are a few Cat5e runs that don't give me 10 Gbps.