Theater is stupid.
There's no scale, no device by which you can measure your talent or potential. You can, as everyone does, compare yourself to everyone else, but everyone else has a skewed view of themselves so YOU must have a skewed view as well! I mean, if you think you have a good chance of succeeding, if you picture yourself on Broadway or in a movie, that's great. But so does the tone-deaf girl next to you and the one-legged dancer girl in the next room.
YOU COULD BE A TONE-DEAF, ONE-LEGGED ACTOR AND JUST NOT KNOW IT.
See what I'm saying? Theater is stupid. Subjective. Impossible to succeed.