Will CircleCI make big $s?

Let's say CircleCi gets 100,000 companies paying their 30$/month subscription (I think that's a pretty ambitious number, or am I naive?) this puts them at 36 million $ yearly income, even today they have over 600 employees - assuming an average of 180k$/y per employee this puts them paying 108 million $ just on salaries. Which part of the story am I missing? what makes investors believe they are going to see big returns?