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Put the users as the focus and make something they will find useful, want to share, talk to people about, feel a part of.
Then you have a useful site that is bound to generate traffic, which you can then monetize any number of ways (including adsense, affiliate programs, direct company sponsorships, etc)
Buying an "adsense ready website" is a shortcut that is going to most likely make more money for the person selling the "ready to go" website rather than the buyer. Without knowing for certain the origins of the "adsense ready website" content, you could also be putting your adsense account at risk