> they are platform businesses, and the value of their services is proportional (or more?) to the size of their user bases. I don't have much to add here, but

> they are platform businesses, and the value of their services is proportional (or more?) to the size of their user bases. I don't have much to add here, but this is known as a network effect. https://en.wikipedia.org/wiki/Network_effect https://en.wikipedia.org/wiki/Network_effect