A bird in the hand is worth two in the bush.
It’s better to have a small actual advantage than the chance of a greater one.
When my informant first heard this saying from her freshman year high school English teacher, she never heard of it before. In fact, she believed that no one in her class understood what she had said, yet she said it quit often. Finally one day, she asked her teacher what exactly she meant by her saying, and from that day on, it has been heard and understood more often.
She distinctly remembers asking advice to her teacher that she got a job offering to work at Baskin Robbins, but was still waiting to hear from Marie Calendars, but really wanted to work at Marie Calendars but Baskin Robbins needed to know that day whether or not. Her teacher then told her the saying, and she then understood. You can risk not having a job for the job that you really want, but then you risk staying with a job that you might hate, yet have financial stability.
Other variations of this saying include A living dog is better than a dead lion in Ecclesiastes IX. The bird adaptation refers back to mediaeval falconry where a bird in the hand (the falcon) was certainly worth more than two in the bush (the prey).