A few days ago I've built https://followgraph.vercel.app in about a working day, and it's just crossed the 10k visitors threshold. Compared to my day job where numbers are in the billions, this isn't much.
But it's still very exciting: I've traded ~8 hours of my time to add value to >10 thousand people. As a rough approximation, that's ~3 seconds per user. If the value they got out of the tool exceeds 3 seconds' worth on average, I've succeeded.