You don't need to be 'mostly' worried about how quickly you can minify for esbuild to be the top choice- if you're only, say, 10% worried about build times and still 90% ('mostly') worried about size + execution speed, esbuild still comes out on top from these benchmarks.
For the rest of us that are 100% focused on the best experience for our users, we stick with the tools that does the best minification while being a bit slower, and throw more hardware at it if needed for the deploys.
And pay more. ESBuild is so much faster that I imagine it could have a significant impact on costs.
Besides, yes you make a good point about the size savings scaling with users, but development speed compounds changes over time.
The choice is a bit more nuanced than "smaller build always === 100% focused on the best experience"
Correction: 10x faster, not 10%. The 60-minute deploy is shortened to 6 minutes, not 54 minutes. This is a significant difference in impact on a deployment workflow.
> we stick with the tools that does the best minification while being a bit slower
Correction: not 'a bit slower', _10 times_ slower, which is significant.