Re: as one of those unicorns
While cloud does has it place for some services, example if you are using an app, having your own infrastructure is a lot less cost. I estimated about 4-6 times less than running in the cloud. This is comparing a co-located rack in a Tier 4 data centre with a SQL cluster, 3 Hyper V host servers, iSCSI SAN all in a redundant setup with Cisco switches & firewalls etc.
Unless you just buy an App you log into be very careful with putting your infrastructure in the cloud.