For people to be so arrogant that they walk around acting like they are the perfect catch and that only the perfect catch will do in their life, is amazing.
It's not necessarily a matter of holding out for "perfection" or "are you good enough for wonderful ME?" It's whether or not you'll abandon your deal-breakers in order to just not be alone.
Maybe you want somebody who shares your faith. You give up and marry somebody whose own faith is so lukewarm they don't care what you believer or not. You have SETTLED. Or you want somebody who will be faithful to you, but you give up and marry a serial cheater so that you won't be alone. You have SETTLED. Or you are raising your children, and you marry somebody who hates kids and is always wanting them to stay at their other parent's home or with friends so he/she doesn't have to have them around. You have SETTLED.