Don't you think the component shortage also reflects big companies when they buy in bulk.
Even if they can get enough servers eventually, they also need more fiber connections and routers so the existing ones can't get congested.
After that they can run in to cooling problems, unless they add the new servers to another facility.
A billion dollars fixes a lot of problems that may come up...
A lot is not same as everything... If normal person needs to wait 3 weeks, Scrooge McDuck might still need to wait one week...
Not forgetting Coinbase uses CloudFlare so it might be CloudFlare that is limiting factor, not Coinbase itself... That error page might be just custom error page displayed by CloudFlare's reverse proxy...
Impossible for us to know for sure. Seems odd that this keeps happening for a company in their position and at this point in their development though.
I've seen a lot of sites using CloudFlare go offline regularly... Only difference is that for smaller clients, it doesn't show fancy error page...