They service those companies as well. Most of the fortune 500 don't buy one server or one storage system. They buy many of everything, and reward the best vendors with larger portions of their data centers, not exclusivity.
"Any" is a strong claim. Alphabet has 60,000+ employees across dozens of divisions and subsidiaries, many of which came through acquisition. It's extremely unlikely that nobody, in any of these groups, is using a Dell server or one of EMC's fifty different models of storage arrays. (Or, to be somewhat ridiculous about it, using a Dell monitor or laptop.)
I'm not sure why you got downvoted - the number of companies that are in the Fortune 500 and would run purely with KVM, Xen, or other non-VMWare hypervisors is pretty small.
For the most part our services compliment our products. You could argue we're a products company that also offers services, or a service company that offers products. Either way, I work in services supporting an in-house product. So at the least, we have both.
So it's a short list of ten for the other 2%. IBM, HP, ... ??
(Clarification: the ten who don't buy from Dell+EMC. Just curious about that. Direct competitors is my first guess ...)