Airbnb didn’t start out with the expectation of listing 1.5 million properties in 34,000 cities in 190 countries. It was a place to book cheap rooms at some conferences when all the hotels were full.
Facebook didn’t start out with the expectation of connecting the entire world! (Almost.) It was a way for mates in uni to keep in touch with each other.
You don’t have to have a plan or even the vision of taking over the world or being hugely successful.
Just start by meeting the needs of the people that are in your immediate vicinity. That’ll do, for now.