JJ is right for the most part, as more than not, history has shown the majority of wiseguys to make their best gains on MLB's moneylines, via it's packed schedules, staggered start times, and moderate predictability.
With college football, due to it's former lack of parity, and every-week-counts schedule making for a nice edge. Especially the well-connected with access to regional info/plays, which is now more widely available via dish/cable tv and websites such as The Rx, yet formerly gave syndicates/LV books/nationwide outs an edge seldom experienced by the masses to regional winners.
NCAA hoops is an earner for those that work very hard, and take advantage of early soft lines to start out on house money, plus allows for nice tourney dollars via dogs, but can be rough for board players, and has rough stretches for those that lack discipline..same as with all sports.
NFL with monster limits can be hit-and-miss even for the elite pros, yet allows for huge spot-plays, and has it's very high probability spots for the patient.
The NBA that once was a consistent winner for those in-the-know(with some specifically totals experts), has become a bit of a cr@pshoot, best used for spot-play and then playoffs, with only the elite insiders and sharps prospering with board play, yet having nice dogs and laydowns for those that work it daily.
The NHL is a hockey-guy sport, that most smarts are simply followers of the hockey-cappers/hockey-group for, yet it has spot-plays, and excellent playoffs, where many sharps that generally don't touch it all year, dive into head first when Lord Stanley is on the line.
Some dabble in horses when given them, some abstain even then, the rest of all sports are in this same mix to the majority..generally only spot-plays as they arise.
These are still just generalities, as each player is different in skills, plus year/season is a different animal, and at times, some lose with their best and win with their worst.