It's not my idea. This is well-known.

As for who pays for it: that's a tricky issue! But if we get into a situation where (for example) 10,000 developers spend an hour a day waiting for builds, we know 50 developers could fix the issue in a year, but that doesn't happen because we can't figure out how to structure it economically --- that would be a failure of organizational imagination.

This is such a low effort sneer-comment, it's a dismissive way to attack and putdown any idea that includes any amount of payment. It's the discussion equivalent of "whoever smelt it, dealt it" - if someone mentions an idea which costs money, demand as a first response if they are going to pay for it (assuming they aren't, instant dismissal), or accuse that the alternative is a kind of entitled and unfair expectation held of others, when neither need be the case.

"That volcano looks like it's becoming active, maybe some sensors could give us an early warning of problems" - Are YOU going to pay for your little "idea"??? Then WHO IS?

"That tree is getting dangeoursly high, it's at risk of falling down in a big storm this winter, maybe we could get it cut down before that" - Are YOU going to pay for it?!

"Dumping raw sewage in the river is making people sick, treating it first would take a small amount of space and a small fraction of the council's existing budget" - and you want to TAX ME for YOUR clean river, I suppose?!

As if OP is the only person who would benefit, as if automatically assuming the worst possible intent for who would pay for it, and as if "who would pay" is the first and only thing worth demanding an answer to, before even having a discussion about whether it's worth doing at all - and which of many ways it might be done.

If the idea involved more than "hire 25 people" then, sure, I might've said something better but just saying more people would solve the problem, is that even an idea?

I think OP meant that companies, like Amazon and MS, whose projects are starting to depend on rust should be putting some resources. Although to be fair, Microsoft and Amazon do pay for their infrastructure if I am not wrong.

Right on both counts.