What is the fine-grained topic of the following text: The online poker behemoth's impact on this event has obviously been profound, as last year's Venetian Deep Stack Extravaganza main event in February had a turnout of 263 players, and the buy-in was only half as much ($2,375+$125). Only return the topic.
Impact of online poker on Venetian Deep Stack Extravaganza event attendance and buy-in costs