When you are immersed in a product that you care deeply about, it is easy to see the warts, the missing pieces, the imperfections. It becomes almost impossible to overlook them or to compare yourself fairly to your competition. It will always feel like "you are not there yet."
The positive aspect is that this keeps you constantly focused on improving your product.
The downside, however, is that you sometimes forget to look up, smell the roses, and appreciate how far you have come.