You will probably never make any money off your writing. You will, however, have shelves full of contributor copies, cupboards full of ramen, unspeakable urges to go to law school or library school or some other semi-responsible thing. You will cry a little each month when you write that frightfully large check to Sallie Mae, or when you can't afford nectarines in the grocery store, when your cats/spouse hate you for not running the air conditioner nearly enough when it's 95 outside. If you are lucky, your health will be good, also your teeth. If you're really lucky, you will publish a book after only spending a small fortune to send it out to contests where you will compete with students / babysitters of the judges and poets who are simply far more talented / lucky than you. Maybe, you will win some small tidy amount of money and get a book out of it. Maybe a small, similarly financially strapped press will take a liking to your work and publish it. You will probably never sell enough books to make back in royalties what you paid to get the book published in the first place but you will politely not notice. If you're unlucky, you will blindly continue shooting off your manuscript yearly to every single contest and waiting patiently with your hands in your laps for someone to notice you. You will grow older and more discontented.
No matter what, you will envy novelists, their shiny publicity stints and reading tours and glossy headshots. And worse, their big advance checks with which they buy new couches and condos and rounds of drinks in expensive bars. You will envy other artists/craftspeople who can make a table, a dress, a painting and sell it, when you are mostly paying people to please (please) take your poems off your hands. You will at times consider becoming a professional dominatrix or phone sex operator, but more likely you will find a string of hopefully bearable but slightly boring jobs that allow you the flexibility and space in your head to write, none of which pay enough to move you into the middle class, but will keep you in postage stamps and entry fees as long as you see fit. If you want, people will pay you to impart knowledge to the next generation of poets on a semester by semester basis in many different places. Hopefully you will make the rent. You will look at their shiny penny faces and resent their innocence. If you are truly lucky you will get tenure, and as you scramble from committee meeting to office hours to class, you will remember to write a poem every once in a while or during the summer if you're nerves aren't fried, shaken, or otherwise completely gone.
You will still want for vacations, trips to the bahamas, jaunts across Italy. Will mend every piece of clothing and wear them until they fray and fade. Sometimes, normal, non artsy people will ask you your income and look at you like you just told them you had some terminal, incurable disease. You will decide money means nothing and yet at the same time you will occasionally find yourself unable to afford bus fare. In the greater poetry world, you will find yourself beholden to rules and guidelines that are both contradictory and completely arbitrary, and will encounter people who will hate you, secretly or openly, simply for being luckier/harder working/more talented than they perceive themselves to be. You will assimilate yourself to hierarchies and structures that mean nothing to people outside of them, who will gaze at you blankly when you try to explain why X mfa program/press/lit journal is more prestigious than Y. You will submit yourself to constant posturing by others during one-on-one or Internet discussions which have a tendency to turn very ugly and personal at times at over rather ridiculous subjects. After all, scarcity, real or imagined, breeds intense animosity. You will witness countless intellectual pissing contests, back-biting, and back channeling. Your complaints about systems and hierarchies and po-biz and such, among fellow poets, will be met with silence and a vague look of discomfort. People will eye you with fear in their eyes at panels or reading as you spout off about self-publishing, debunking, and de-centering. Afterwards, they will politely shake your hand and move away from you as quickly as possible as if you might suddenly bite them or throw up on their shoes.
Amidst all this you will still love poetry, even though poetry does not always love you back, even though sometimes you have to coax her away from the ledge with shredded paper and chocolates. You will hoard poems in the bureaus, on top of the fridge, in your desk drawer at work. You will still consider library school and law school and phone sex, but maybe if you're lucky you will make your own way trailing your poems along behind you like breadcrumbs. And just maybe, someone will pick them up and flip you a quarter now and then.