Funny, some pro photographers are good, some are not, but I don't remember ever thinking "I can't be that good" - and in particular I have never thought "I can't be that good unless I'm a pro". Racing drivers may be different as that is a very expensive sport. For most of us, we really can't be that good unless someone else is paying for us to break cars. In some photographic fields it is necessary to be a pro as the gear costs too much - or be very rich to start with, but most still photography is within the reach of many of us.