You don't win a World Cup as much as you will a World Cup.
The last three finals ended in a draw at full-time. Eight of the last 12 have been decided either by a single goal or in extra-time or penalties. Once you get there, it's as much about nerve and randomness, blades of grass that make a ball bounce just so or specks of dust that make you react that split-second later, as it is about who is objectively better.
Bear this in mind when looking at Russia 2018. Because while there are four teams (Brazil, Spain, Germany and France) who are clearly a notch above the rest -- and who, were this a traditional home-and-away round-robin league, you'd expect to finish in the Champions League spots -- little is guaranteed.