All of these can be summed up as the chicken-and-egg paradox, or network effects. You need users to make the app useful, to get more users, to make the app usef

All of these can be summed up as the chicken-and-egg paradox, or network effects. You need users to make the app useful, to get more users, to make the app useful. Look at how other business get around that, e.g. facebook launched to just one market first, Harvard students, then slowly expanded out one market at a time.