When a player is bragging that in ANY game you can hit an unbelievable high lvl in 2 days is :

1. a freaking nerd that plays 15 hours a day.
2. he knows everything about the game already.
3. he has already lots of money to start with.
4. might have a friend to help going through quests/grinds.
5. CS items.
6. everything above stacked together.

Of course it's probably not possible to any other player that just started and play casually and within reasonable playing time.