References to the advantages of being a host nation have made me curious, so I have had a little rummage.
In the 16 world cups since WWII, beginning with 1950, only 4 host nations have won the world cup. England, to my surprise, were actually the first to do so, followed by West Germany (74) , Argentina (78) and France (98). An additional 2 host nations were runners up (Brazil 1950, Sweden 1958), while 4 lost in the semi-finals.
In other words, being host nation is certainly no guarantee of success; only 6/16 have made the final, 4 going on to win it. On the other hand, of the 10/16 host nations who made the semi-finals since WWII, 6 have gone on to the final.