It adds up but it would require to rewrite all software, which would be pretty costly.

I agree with the sentiment but it's a bit too late now.

The problem is with how software is designed around being cheap to write.

It's so much cheaper to optimize now than before.

What is this based on? Could you expand on this a bit?

Just personal experience using LLMs. I've optimized a lot of things in the past year I wouldn't normally have time to do, especially build systems/pipelines.

It's just Brave browser, you don't multiply by the number of every kind of service

With your attitude towards improving one piece of software, it becomes every piece of software.