Then yes, everyone is taking advantage of everyone. My cell phone provider is taking advantage of me because they make profit off of me. I'm taking advantage of them because they spent $1,000,000,000 building the infrastructure so I can use that cell phone. Apple is taking advantage of me by making a profit off of their cell phone. I am taking advantage of Apple by using that phone which they put millions of dollars of research into and shipped to my door.

So we both gain an advantage.

Jack gets a job with Amazon - he is able to afford a color TV and internet at home. Amazon hires Jack - they get their orders shipped to homes on time for Christmas.

Everyone is getting an advantage in all of these situations. No one would ever make an agreement that doesn't provide an advantage.

I assume you're asserting there is a power difference between Amazon and Jack that makes Amazon get more advantage from Jack. This may be true. Amazon, however, has a power difference with customers who ultimately decide whether the billions of dollars worth of infrastructure they are building is worth it or whether competitors will win.

Is it wrong if I decide to not buy from Amazon? Am I taking advantage of them by buying if their product is $10 but not buying if their product is $12?

"Taking advantage" does not mean "getting an economic benefit out of a transaction with someone." It's a moral judgment, defined in terms of conformance with social norms and expectations.