Many read product reviews from Amazon.com, but some of those reviewers may be getting products for free.
The reviews that appear first are from top reviewers, who likely did not purchase that toaster or television.
Instead, those people are part of Amazon's vine community. Amazon sent them the item free of charge to try out and keep. The only requirement is that they must not sell it.
Amazon chooses this method because it says it's the best way to get unbiased reviews, reviews that are written well and avoid complaints.
So take those reviews with a grain of salt, so you don't waste your money.