Amazon, Microsoft and Alphabet have economies of scale which help them advance in cloud computing.
Amazon, Microsoft and Alphabet and Amazon specifically have a first mover advantage which brings momentum and enlarges Amazon, Microsoft and Alphabet's distance with their competitors.
Another lane in the cloud computing business is populated with start ups like Hashi Corp and GitLab which are carving out their niches. Both Hashi Corp and GitLab are innovative, agile and fast moving which is typical for smaller start up organizations. It must be said that both Hashi Corp and GitLab would soon ne difficult to define as start ups as they are growing briskly.
Both the established companies and new start ups in the cloud computing business provide a way for firms to save time, money, and effort. This is basically done by writing and successfully putting into production software code which performs cloud computing services and also providing the needed server storage and computing power to support the cloud.
Since most firms are very far away from the expertise in code writing and software production of Amazon, Microsoft and Alphabet or Hashi Corp and GitLab it is much more efficient for most firms to outsource cloud computing to the aforementioned firms.
And scale brings scale with it. That said, cloud computing is such a large business already in terms of annual revenue and with such a huge promise that the field is open for many other new entrants to enter, develop innovative products and enhance both their value and the value for society.