I mostly agree, but optical transceivers are still expensive. Been waiting for dirt cheap silicon photonics for a couple of decades now. But it seems they are on track to be a thing, though initially for high-speed networking not home/office type stuff. Maybe one day, sigh.

I'm not sure how you define expensive. https://www.fs.com/c/10g-sfp-plus-63

20 bucks over MMF, 27 bucks over SMF doesn't seem expensive.

If you want to do it over single fiber rather than duplex, it's 40 bucks: https://www.fs.com/c/bidi-sfp-plus-64

25Gbps is 39 bucks over MMF, 59 bucks over SMF. 40Gbps is also 39 bucks on MMF (more expensive on SMF)

I don't think any of these are very expensive.

The cards are also ~same price between SFP+ and 10GBaseT from places like startech (outside of that, the 10gbaset ones are actually often much more expensive)