Not only in accumulated bet both in single bet, because there are some people who always base on a single bet and they will still end up experiencing lose. So whether accumulated bet or not so far as is gambling, of course luck always play it roll. even if you want to apply the whole gambling skill, You will definitely experience lose one day, so the fact remains that gambling is just a luck based.
Now sports betting is not just based on luck. We know gambling depends on luck, but casino games and sports are different. In casino games you place bets that have a 50% chance of losing or winning. But in sports betting you need to see if the team is good, see which team's players are performing well, see the head to head record, see if they are playing at home. Now skill in sports betting will give you advantage but cannot guarantee you win, if you are not lucky then you won't win. But betting without analysis in sports betting is foolish, so bet with analysis.