Do you know what happens to the money that would be spent on printing when an ebook is sold?
The cost of printing is a very small component of the cover price of a book; for paperbacks you're talking around $0.5, and for hardbacks around $2-3.
The author and publisher get roughly equal shares of the profit from a traditional trade book sale; the lion's share of the profit goes to the retail distribution chain, i.e. Amazon. (And when I say "lion's share" I mean 30-70%, depending.)
The author's cut is a royalty percentage of net receipts. And yes, I get a much larger percentage cut of ebook sales than paper sales -- it comes from what would otherwise be the physical dead-tree printing costs.