Billions of dollars spent means nothing unless it actually takes billions to launch a hosting company. It doesn't.

You'd need to have some damn clever and hard to copy idea to have any competitive edge.

When Google and Amazon are not making their own specialized hardware (good luck implementing your own TrueTime or TPU or competing with them with ML or DB products built on off-the-shelf stuff) they get custom made chips at prices you can't by Intel et al and have things like a very sophisticated SDN backed by a private global physical network infra and enormous amounts of expertise of building and running very efficient DCs. And then there is a software stack which often is literally more than a decade ahead of industry practice.

All the things you list are not a part of the moat to compete with the big providers. They are barriers to becoming as large as them. But 10,000 smaller hosting companies could easily start to cut in on their long tail customers. Most any mid size hosting company could handle the traffic and compute of 95% of companies out there.

You still haven't given any indication what those mid sized hosting companies would hope to compete on for the "long tail customers". Even if all the scale advantages Amazon and Google have currently don't translate into better prices across the board (mostly because they like those margins on e.g. network egress and they have sufficient lock-in for most customers) why, as someone in charge of provisioning cloud facilities for some small or mid-sized company, would I even contemplate going to a competitor?

What's gonna be more useful CV and CYA wise? Who's ever been fired for choosing AWS? How is being expert in <obscure hosting provider> going to advance my career? Where do I hire people who know about <obscure hosting provider>? How would I even realistically learn that <obscure hosting provider> might be a good fit for my needs?