In fairness, if someone told me they were going to make a killing on free webmail supported by ads and data mining, I think "How on earth do you intend to complete with Google?" would be a perfectly legitimate question.
Or it will get done by people who have thought long and hard about how they are going to compete with the giants, rather than someone naïve sap.
The fact that the question is being asked does not imply that there are no good answers to it, but it is unlikely that someone who hasn't spent time considering how to improve on the incumbents is going to beat them.