It makes sense to plan ahead for increased scale. If you are working for a VC backed company whose mission goals are to grow grow grow scale scale scale, then you cant exactly build for the infrastructure you currently are using. Its perfectly acceptable to build out an overbuilt infra, as long as your costs aren't shooting you in the foot. You know whats worse then paying too much for infrastructure? Loosing money and clients because your infrastructure breaks anytime you get a real workload on it.
But even worse is not being able to release because the system complexity has shot through the roof. Plan (and test!) for 10x scale at a time, then optimize to squeeze another 5-10x while you build the 1000x system.
