I think you get 1 free article...which would enable you to get past the paywall.  If not, you should be able to obtain access through the google machine.  In any event, I've excerpted a couple of paragraphs.  

https://www.barrons.com/articles/draftkings-flutter-stock-sports-gambling-parlay-bet-25914b0f?mod=hp_HERO

In Illinois, which releases the most specific data about betting activity, parlays now account for more than 60% of the total number of online sports bets that people make each month and more than 27% of the money wagered, up from 20% two years ago.

That shift is no small matter to the two biggest sports gambling companies, DraftKings DKNG 5.91% (ticker: DKNG) and Flutter Entertainment FLTR -2.58% (PDYPY), the owner of FanDuel. Parlays have allowed them to make much more on each wager. The companies don’t regularly release details on just how profitable parlays can be, but a Barron’s analysis of data released by state gambling regulators shows that the companies’ average “win margin”—the amount they keep from bets—is about 20% on those bets, versus 5% for a standard bet on a single outcome in baseball or football. 

Those growing margins help explain why DraftKings stock is up 150% this year and Flutter has climbed 36%, more than twice as much as the broader market.