Is there a market, a bet, and odds? How is this different from sports betting? Why isn't a casino called a casino but a prediction market? Why isn't an opening called an opening but an opening and closing contract?

The US-Iran conflict has generated $600 million in bets, and Polymarket has launched multiple related contracts.
On March 1st, after the US and Israel launched airstrikes on Iran, the decentralized prediction platform Polymarket quickly launched more than ten contracts related to the US-Iran conflict, with total bets exceeding $600 million.
Among them, the contract "Will Khamenei lose his supreme leader position before March 31st" settled at 100% after his death was confirmed, with a single market trading volume of $45 million; since its launch in December last year, the "Will the US strike Iran by a certain date" contract has accumulated a trading volume of $529 million, becoming one of the platform's largest markets in history.
Additionally, the contract "Will the Iranian regime fall before June 30th" currently has a probability of 54%; the contract "Will the US deploy troops to Iran before March 7th" has an approximate probability of 28%.
On-chain analysis firm Bubblemaps pointed out that six wallets precisely bet on "The US will strike Iran on that day" before the airstrikes on February 28th, collectively profiting about $1.2 million, raising questions about potential insider trading. $ETH
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