Pretty sure it limits you to a set number of pages from any given book per day or something. I'm sure with sufficient effort you could work around it but a casual user can't just work their way through a complete book.
So after 100 days you'll probably still have 100 incomplete books.
2: This is not Google's first rodeo when it comes to scraping. I'd be surprised if you got more than a few days into the described process, so no, it certainly does not scale.
Google actually thought this through.