Online betting is now legal in all 50 states and record sums are pouring in, which is good for the betting platforms and bad for the young men they target.

• A record $14.1 billion was bet on prediction markets in one week, powered by the NFL season opener and the US Open.
• LeBron James, Eli Manning, Spike Lee, and Sydney Sweeney are fronting ad campaigns for Polymarket, Kalshi, and Novig, pushing them to the top of the app download charts.
• "Prediction markets" now offer quarter-by-quarter spreads and parlays that are indistinguishable from sportsbooks — FanDuel itself is quietly taking the other side of many of those bets.
• Parlays are where the houses make most of their money, and most people betting them lose with predictable regularity.
• These markets sit outside normal insider-trading rules: a KPMG employee is under investigation for betting on earnings of companies his firm audited, apparently to dodge the SEC.

Outlook: Expect the money and the advertising to keep growing through the NFL season, with regulators far behind and addiction and insider-betting cases piling up.