No, it won't be worth billions, that's kind of the point. It should be possible to do it efficiently so that the operating costs are low and it doesn't need to make billions in order to be sustainable and outcompete the incumbents.

As to why I don't do it, maybe I will -- but I wouldn't object if someone beat me to it. Because it still requires some combination of time and money, the amount of which can be feasible without being zero, and it's quite likely that of all the people in the world, someone who isn't me is in a better position to pull it off before I do.