Paul Graham says that many of the biggest companies initially start out as toys, or solve small problems [0]. Gates and Allen thought about whether they could create a BASIC interpreter and sold it, for example, and used that to eventually create Windows.

You can't know whether your company will be a billion dollar one ahead of time, unless you're really working in a large problem space, such as biotech, space exploration, etc, but it doesn't look like you are. Therefore, just solve the problems you have, make money (preferably without raising venture capital), then use that money to fund your business and hire employees.

Check out Indie Hackers for more examples of profitable internet businesses [1].

[0] http://www.paulgraham.com/startupideas.html

[1] www.indiehackers.com