This calculation of how much money and time does a person need for a world tour is totally dependent on the mode of transport and style of living. If you travel by flight it may take 2 hours to reach from distance A to B, whereas the same distance if you cover by road may take 12 - 18 hours. And same way the living expenses. People can spend $10 to $200 per day based on their style of living and eating.
Roughly it is estimated by a travel enthusiast that it will take an entire 3 years to go around the world and $150 K for expenses.