[2muchcoffeeman]

There is no gambling involved in buying a book. I give you $X you give me a book.

Gambling is I give you $X I have a,b,c % chance of getting A,B,C. Usually I get nothing. Nothing I can do can effect the outcome.

Colloquially, you might say "I don't like this author, but the reviews say blah was a blah, so I took a gamble". But that is clearly not the same as pure chance gambling.