I can see them making money, I'm more shocked at the cost of running or building it up. I try to assume that if I think something is odd but it's not my field,

I can see them making money, I'm more shocked at the cost of running or building it up. I try to assume that if I think something is odd but it's not my field, I'm wrong and don't understand it properly. It's just at a scale I find hard to understand. A billion dollars is a lot. I'd love to know what it is they're pumping the money into that they make per user, because I can't see what massive upcoming things there are to build. What are they ploughing hundreds of millions into? Again, with all of this, I assume it's me that doesn't understand.