Google did just that with G+, Hangouts, Checkout and a whole raft of others. Even if you don't become #1 you owe it to your customers to plan ahead and to ensure a business is 'unit cost profitable' at the scale at which you offer it so that you can sustain it.

Going for broke on projects and then canning them when they fail to attract the kind of success that a smaller company would be more than happy with is in the long run a losing bet.