Of course I don't know what Tolkien was thinking....
But 50 is a great age for adventure. You've tried just about everything you wanted to try, at least once....you're beginning to get a little bored doing what you're "supposed to do".... you've learned enough to appreciate most things for what they are worth....and your love life isn't controlling you anymore! Both Bilbo and Frodo were bachelors, so why not.
