As you just saw, when deploying in the cloud, you only pay for the resources that you are provided with. Most cloud companies use this to their advantage, in order to scale their infrastructure up or down as the traffic to their site changes. This ability to add or remove new servers and services in no time and on demand is one of the main differentiators of an effective cloud infrastructure.
In the following example, you can see the amount of traffic at https://www.amazon.com/ during the month of November. Thanks to Black Friday and Cyber Monday, the traffic triples at the end of the month:
If the company were ...