"A bird in the hand," is yours, and it's not going anywhere unless you let it go. But if you leave it and go for "two in the bush," there is no guarantee you'll catch them, you might end up with nothing in the end.
In essence, don't be greedy and stick with what good things you already have, instead of going after something you'll probably never get.
Joe: "Are you sure? You probably shouldn't quit unless you know you're gonna get in for sure. A bird in the hand is worth two in the bush."
Joe: "So how was the interview?"
Bob: "Idk not so good...i don't think the boss is gonna let me come back either..."
Joe: "You're an idiot.."
Women are sometimes not worth the hassle, headache or monitary cost to keep around, despite giving you sex.
Greg: Oh yeah? What for?
Rob: I don't know, she wouldn't tell me. I bet she's cheating on me.
Greg: Why do you think that?
Rob: Well she borrows money from me all the time, and I'm stupid and jump to conclusions.
Greg: Well, my dad always told me that a bird in the hand is worth two in the bush.
Rob: You're right.