It's really just perception. If you meet and exceed a higher goal, it may appear to be more of an accomplishment than exceeding a smaller one.
However, we encourage most organizers to start with a more modest goal (100 or 250) to allow them to gain some early momentum. Keep in mind that the goal can be raised later.
To set a custom goal that's outside of our defaults (100, 250, 500), upgrade to our Storm, Pro, or Enterprise plan.