I've been developing a live betting system in soccer, and I made 44,73 units over 101 plays http://prntscr.com/34eb1u
ROI: 23,4%
Feels almost too easy to be true, but it doesn't look like it should stop making profit, unless I get limited by the books, but that won't be any time soon at my stakes.
This is a brag thread, but it should encourage you to look into live betting. There is a way to grind value in other sports, too.