Writing any novel worth it's salt is a long and painful journey that often is nourished by your tears. There is also the sheer amount of frustration from both characters and scenes just not wanting to go how you wanted. If you are not on the verge of tears you are close to just saying "fuck all!"
So you managed to get passed all that and the occasional writers block? Yay! You are still not done. Now you need to self edit and find an actual editor who is going to cost money. Guess what? Those are expensive running on the low end of fifteen dollars an hour spent on your manuscript. Now guess what? This isn't going to be a one time deal here, after the do an initial edit you go in and change what you want and make your own changes based on what they edited and then, thats right, they have to edit it again. This could go on for months!
Now that is out of the way time to send off to publishing houses to be looked at, this is assuming you are skipping the part where you should get an agent. Each firm can take up to six months to get back to you and more than likely tell you no. So you have to keep sending it out to the limited publishing houses you have access to or get a damn agent.
So you want an agent now. Well you need the right one for you. You just can't pick one at random and hope for the best your book will never sell. You need an agent who likes the genre you are writing in who will understand your targeted audience and send your manuscript to the right publishing houses. So this hunt can take up to months as well.
But you have one now, and you will still face rejection left and right, but now you have more options and eventually someone says yes. Now it's going through all the paperwork and rights stuff to make sure you don't get fucked over and the publishing house doesn't as well.
Finally after all that your book goes to print.
So easy right?