Honestly it's mostly a novelty for me, I did it for bragging rights and out of curiosity.
1Gbps to 10Gbps has some tangible benefits like downloading large games in a fraction of the time, or doing super fast backups.
However when you have 25Gbps, you have a pipe twice as large as is common in standard hardware. You usually see yourself limited by 10Gbps peering links or by endpoints with only 10Gbps NICs.
And of course 25Gbps is faster than most conventional storage, you need very high-end NVMe or RAID to keep up.
If I'd have had to pay a bit extra every month, I probably wouldn't have done it. But since it was just the price of the hardware plus installation, I thought it was worth trying.
Previously, on HN I remember seeing this post
https://news.ycombinator.com/item?id=31134534