Even if you have 100 billion dollars in the bank, you're years behind. Go buy land, build datacenters (5 year lead time), sign power contracts with utility providers, figure out where to buy all your dram and disk and networking and shit and oh develop your cloud services too. Now keep them running.
To add on to your point: Amazon told Jassy in 2003/2004 to take 55 engineers and build out some cloud services they could sell to customers. ~6 years later, Microsoft decides to enter the market.
That is an epic first-to-market timeline.
Building out those services is a monumental task requiring loads of experts in their respective fields (databases, storage, networking, etc). I see this as at least as much of a hurdle as the capital expenditure.
Not only do you have to have the physical infrastructure to launch a region (expensive in and of itself), you pretty much have to have the infrastructure to launch at the minimum two regions geographically separated in some form. Plus with data locality laws increasingly enter the mix (something that AWS never had to worry about until they were already a success), you increasingly have to build regions everywhere or customers can't use you. Frankfurt, for example, is a virtual given.
That's before you even start to consider all the engineering work involved writing the code to run the cloud services.
Once you had enough demand to merit your own data centers, then would go ahead and build them. Thats what most VPSs do.