a bird in the hand is worth two in the bush
Having one is better than seeing a whole bunch of them, especially if they're all trying to steal your spot.
He had one girlfriend, and he left her for a bunch of girls who all wanted him.
She had one job, and she quit for a bunch of jobs that never paid her.
He had one slice of pizza, and he went for two slices from a place that didn't even have cheese.