Once, a prospective client didn't sign with me because she'd heard me say "most writers don't earn a living from their work". She thought it was defeatist talk, and since she was sure she was the exception to the norm, she signed with someone who didn't tell her she'd be lucky to break even.
Eternal optimists, and you-control-your-destiny Tony Robbins and Tom Cruise (who I think didn''t graduate from high school but by god don't let that stop you from listening to his opinions on medical topics) aside...do you know the difference between reality and going in hock up to your eyeballs because you KNOW you're the next Big Thing?
As an agent my job is half cheerleader and half mother in law. Guess which part is more fun. Yes, we cheer you on. Yes we WANT you to be the next Big Thing. (Remember I make fifteen percent from all those lovely Big Thing Bonanzas so I'm VERY interested in you being a success). But, I've been here a long time. Most of the authors I have these conversations with haven't.
The truth is..keep your day job. And save a lot of money for promotion cause writing books is a HOBBY for most people. If they are LUCKY, they make money one year in three. Not all of course. But MOST. And unlike Lake Woebegone, dear snarklings, we are not all above average.