Under 20% vig in motorsport markets is as good or better than 5Dimes ever offered. And they were always at least 5 points cheaper than any other book. Plus they release lines on Monday mornings. 3 days before most.
I know that's not mainstream sport, but it's not the only example.
Plus if you combine KAMBI backend with a pretty amateurish new crew like BetMGM have, who move live lines on several sports up to a minute after Draftkings do, it can work out well