All three are totally dependent on cloud services to power revenue growth in the forseeable future. Amazon's retail efforts aren't where the big exciting growth for investors is, it's all AWS. Windows/Office has been stagnant for a long time, or even in decline. MSFT price only took off once Azure took off. And as for Google, well, what exactly are they doing that's new other than GCP? They've got nothing that can absorb growth at their scale.

If you look at the costs of the big 3 tech firm cloud solutions relative to what you can get from smaller providers, it's an enormous markup. None of them are going to compete with each other on price because that'd void the point of doing cloud to begin with. Plus tech firms hate competing on price. It signals to the market that you've run out of innovations.