You are painting an incomplete picture. Between high (racking your own servers at multiple DCs) & very-high (your own DCs) CapEx options and low CapEx options (IaaS and PaaS), there is a middle ground that - unless you need specific managed services, the larger PaaS ecosystem and/or an extreme scalability - is to use bare-metal cloud providers. This approach combines multiple benefits, including bare metal's max. performance, full isolation / no "noisy neighbors", pretty much total control of the equipment that you rent, cloud-like elasticity, flexible, usually globally distributed, network architecture and reasonable pricing.