I've got some bad news, writers. In comics, the artist works harder than we do. On a simple one to one basis, they just plain work harder. A writer can easily write a script a week (or at least, should be able to.) An artist has to spend an entire month on the art. That's a 1:4 ratio. That means that when there's money to be had, the artist deserves to be paid first. You, as a writer, can take other jobs. You can have a day job and still do your job. An artist, delivering on a monthly book, 99.9% of the time, can't. It might be 'your idea' and you might have spent 'months researching it' but, this is a collaborative art. It's a partnership. You and your artist are married, but, as unequal partners. You can sleep around with other artists, they're stuck only with you.
And. They. Should. Be. Paid. For. That. Loyalty.
I've heard a few stories from a few friends who are in situations where there's an advance or a page rate and the writer takes 50% leaving the artist with their 'fair' share, which is not enough money to actually live on AND execute the project. I was shocked BOTH times, but I suppose I shouldn't be.
Everyone THINKS they work hard. Hell, I think I work hard. I'm writing 5 creator owned series, a work for hire comic series, plus working on a tv show and a cartoon series. And y'know what? I still have more free time than any of my collaborators.
Should everyone profit from the collaboration, absolutely, but, advances and page rates those are not profits. Those are costs. Those are the hard costs of the sacrifice your partners are making in order to complete the project. Do I wish I could get paid up front for my creator owned work? Absolutely. But you know what I prefer? My partners making a living wage that allows them to actually MAKE THE BOOKS.
Caveat, obviously, every situation is different, and in full disclosure, on one of my books, there is no page rate, and the profits are minimal, and the artist and I split that money 50/50, but it's by agreement, not by greed. Y'see, we've always treated each other fairly, so when we saw what the financial outlook of the book is we had a conversation about it. I didn't just decide to take that money.
Long story short. Don't be an asshole. Appreciate that your partners are undoubtedly working as hard, more likely, harder than you are, and give them the support and love they deserve.
ADDENDUM: The same goes for colorists, inkers, letterers, and, yes, even editors. We are slugs compared to the lives of almost all of our collaborators. Except for publishers. They're lazy fat cats. Maybe not all of them.