Where your rack is is basically not relevant. For most startups, AWS is great, even if it's more cost of colo, it's the opportunity cost and dynamism it offers. Use AWS until the savings of not doing so will not affect your ability to grow, or costs are not dreadful. Moving away from AWS is a cost optimization, it depends on the kind of business you have.

But more broadly, the value is IP, essentially know-how and lock-in with customers, relationships etc..