Who is believed to be the main reason of so called "Poker boom"?

The impact of the boom was escalated in May 2003, when amateur Chris Moneymaker won the 2003 WSOP Main Event. Moneymaker won his seat via a $39 satellite tournament on the PokerStars online poker room. Moneymaker was one of 839 entrants in the 2003 event. By the next year, the field in the 2004 Main Event more than tripled to 2576 players. By the 2006 Main Event, there were 8773 competitors, some 14 times as many as had entered the last 2002 pre-boom Main Event.