Some people love and knows everything about soccer why some people love and knows everything about basketball, so also table tennis, volleyball, baseball, horse racing, handball, snooker, boxing, cricket, golf etc. Any sport you know very well, you can gamble on those sport and avoid gambling on sports you know nothing about, one of the reasons why some set of people lose money a lot when it comes to gambling is because they gamble on sports they know nothing about with the slogan " gambling is all about luck" yes gambling involves luck but that those not mean skill and knowledge is not involve, if you gamble on sports you know nothing about then you are gambling blinding and your chance of winning are very small compared to when you know everything about that particular sport, when you know a lot about a particular sport prediction will be easy for you.
Is true that knowing everything about a particular sport those not grantee you winning always but is an added advantage when you are gambling because it brings you more wins.
Agree that we should only bet on sports that we understand, but losing often can be not only because we bet on sports that we don't understand but also because we ignore data about the athlete or club, either because we are fanatical about the club or athlete or because we prefer big odds because we think the profit will be bigger.
I can't even understand why any bettor would bet on a sport they don't understand, because luck doesn't play a big role in sports betting, there are analytical skills that can increase the chances of profit.