The difference between wishing and building is what you do after the excitement leaves.

Starting is enjoyable and tells you almost nothing. Everyone is capable during the phase when the idea is new and the imagined version of the finished thing is still perfect. What separates a wish from a thing that exists is what happens in the middle, after the novelty has gone and the work has revealed itself to be ordinary. Building is mostly that middle.

When the excitement fades, treat it as the beginning of the real project rather than a sign you chose wrong. Reduce the daily demand so it survives the dull stretch. Then keep going long enough to find out whether the idea was actually any good.