I’ve never entered a professional competition. I’ve been on a committee or two (not related to art) for them, and known others who were involved in running them. My experience from that side of things has been that the competition isn’t usually based on just talent or the excellence of an entry. There is usually some criteria, a style or theme or certain rules of art, that the judges are looking for. It almost has to be that way – otherwise, they would be overwhelmed by the number of entries and trying to decide how to compare apples to oranges.
Generally, I try to avoid things like this. That’s personal, though. I’m not much on competition over all. If I do enter something, I try to remember that not winning isn’t the same as losing. It just means the entry didn’t meet certain criteria that has nothing to do with my talent or the value of my work.