1. You don't have to shell out money for three extra major presents a year.
2. You get to pick your own mattress.
3. You can take a job anywhere on earth without making someone else move.
4. You've had time to experiment and figure out what you like sexually, and you don't feel guilty asking for it.
5. You get to choose all your own friends.
When you marry someone, you not only marry their family, you also marry all of their friends. Being single means that you don't have to hang out with that one person you can't stand because your SO went to college with them, and still thinks of them as how they were then, and not how they are now, which is awful.