• The American Gaming Association estimates 7.2 million people will place online wagers for the Super Bowl and generate $4.3 billion in bets.
• Interesting wagers include a $3.4 million bet on the Tampa Bay Buccaneers winning via DraftKings and if the opening kickoff will be returned for a touchdown on FanDuel.
• Meanwhile, secondary ticket agencies experiencing decline in prices but that could change, Gametime's Jeff Gurian told CNBC.

The National Football League's Super Bowl LV is set to make history on the gambling front.

Sunday's contest between the Kansas City Chiefs and Tampa Bay Buccaneers is expected to draw $4.3 billion in bets, according to the American Gaming Association (AGA). The firm said 23.2 million people will place the wagers, including 7.2 million online.

Bill Miller, president and CEO of AGA, said the game is expected to be "the largest single-event legal handle in American sports betting history."

"I think it's a testament to and further evidence to how pervasive sports betting has always been in our society," FanDuel CEO Matt King told CNBC on Thursday when discussing the projection. "Part of the reason you're seeing the legal market grow so much is as states legalize, we are taking market share from the illegal markets."

Sports gambling is now legal in 20 states after companies joined Virginia's market this month. Firms used 2020 to build awareness around their mobile apps as they position for legal market share.

According to advertising tech firm MediaRadar, FanDuel, DraftKings, and Bet365 spent a combined $200 million on ads over the last year to draw customers. The firm told CNBC it used aggregated advertising data from media channels including TV, online and print to determine the figure.

With attention now centered on Super Bowl wagers, some interesting bets taking place includes a Texas man flying to Colorado to place a $3.46 million wager with DraftKings on the Bucs, the company told CNBC on Thursday.

The point spread has the Bucs at +3.5. That means they are the underdog team, and to win the bet, the Bucs need to win outright or lose by three. If the man wins, he receives his $3.46 million back, and DraftKings will pay him $2.74 million.

"Looking at the way we have booked the Super Bowl so far, bettors are laying -3 on the Chiefs and taking the Buccaneers at +3.5 as fans try to get the best possible line," said Johnny Avello, DraftKings' director of race and bookmaking operations.

On the BetMGM side, a person placed a $2.3 million wager (payout of $2 million) on the Bucs at +3.5, too. The firm also took a money line bet (wagering that a team will win outright) of $180,000 on the Chiefs (-180). A win would net $100,000.

Meanwhile, FanDuel has unique bets, including a prop bet on rushing yards. A bettor can wager any player will rush for more than 100 Yards. If it happens, bettors win $260 on every $100 they bet, and if it doesn't, the win is $100 for every $370 stake (Yes +260, No -370). The firm notes that less than 20 players have rushed for more than 100 yards in a Super Bowl."

Another bet: If the opening kickoff will be returned for a touchdown. Bettors can place $100 that it will happen and win $5,500 if it does. FanDuel notes the play has only happened once in the history of the Super Bowl.

King said "same-game parlays" around Super Bowl LV, where bettors can customize and combine a series of unique FanDuel bets to their liking, has been drawing interest.

"They are usually betting $5 on it but find it to be a lot of fun," said King, adding the company took in roughly $1 billion in overall bets in the first 28 days of the year. "They like to see the biggest odds they can get, and it's fun to see people interact with that product."

Super Bowl ticket prices are a rollercoaster

On the attendance front, experts are comparing secondary Super Bowl LV ticket sales to GameStop's stock volatility as prices continue to fluctuate.

Super Bowl LV tickets were initially estimated to be some of the most expensive in the game's history, but prices have fallen in the last week. Last-minute ticket agency Gametime said "get-in" (cheapest ticket) prices are now under $5,000, falling from $11,000 last week.

Hence, early buyers hoping to sell for more could be disappointed.

On Jan. 28, data from rival secondary agency TicketIQ saw prices reach $73,527 for expensive seats and get-in prices around $7,274.

Jeff Gurian, Gametime's vice president of performance marketing, told CNBC tickets were "probably priced initially to reflect the initial demand and the uncertainty around supply. But maybe prices were too high and scared people off."

He also pointed to the Bucs' appearance as a reason prices declined. They became the first NFL club to play a Super Bowl in their home stadium, so local fans can wait for bargains with no airline and hotel expenses.

"They can sit on the sidelines and wait, and maybe that is what they've been doing to see if prices decline because they can decide last minute if they want to go or not," Gurian said.

He added Chiefs fans have already experienced the team's 2020 championship and could be reluctant to travel with the pandemic. The limited Super Bowl Experience could be another factor, and the host city isn't as attractive as last year's destination in Miami.

"I would advise a little more patience but not too much," said Gurian of a last-minute buying strategy. "Last year, prices did increase in the week before the game, and there is a chance that people are waiting and then start buying last minute. And then, prices will increase again. There is probably a sweet spot to buy in the next few days."