(USA) If someone is trying to convince people to do or feel something without any hope of succeeding, they're beating a dead horse.
This is used when someone is trying to raise interest in an issue that no-one supports anymore; beating a dead horse will not make it do any more work.
This means that it is better to be the head or at the top of something that isn't very important or prestigious than a small or unimportant member of something big.
If you aren't interested in something because it isn't important to you and there are more important things for you to do, you have bigger fish to fry.
'A bird in the hand is worth two in the bush' is a proverb meaning that it is better to have something that is certain than take a risk to get more, where you might lose everything.