This is absolutely untrue in both a naive and more nuanced sense. Naively, it's not like an airplane, it's like an airplane rented by the month: the owner of the airplane collects rent whether or not the airplane is flying. More nuanced, many VPS providers don't sell you 100% CPU utilization; they sell you a compute budget. AWS actually enforces this; I don't know about other providers. But if you're exceeding your compute budget and the provider doesn't enforce the budget limit, you can expect the system to break at some point.