Two years without chargers, new 20W sold for $25, so $23 in profit according to you.
Profit from charger sales = 200,000,000 units/year * 2 years * $23 profit = 9.2B. Obviously not everyone buys a charger, and obviously your numbers are estimates, and so are the articles. The real number is obviously less.
Don't forget to add the profit from every phone sold at the same cost without a charger:
Profit from cost reduction = 200,000,000 units/year * 2 years * $2 in profit for every sale = $800M in profit. The real number is higher as you claim the real cost is might be somewhere between 2-3/unit.
Obviously the numbers above are just random estimates based on the numbers you provided. However, billions of dollars in profit are a reasonable estimate, and I'm inclined to believe the articles over you, as well as the basic math you didn't do.