To be honest, betting on sports is more logical thing to do for people who are keen to watch sports.
It involves a skill of analysis and research which makes our probability of winning more.
The same goes with skill based games like poker but yeah, for sports betting, we can only have the edge if we do a thorough analysis on the game.
Sports are exciting and sport bets are interesting too, but as same as all other activities, you as a participant or an outsider or observer, can not control everything. As a gambler, you can make your bet but you can not control what players do in the match or fight. Even these people as direct participants of matches, fights can not control their ending as winner or loser.
So no matter how experienced you are in sport bet and how much knowledge you understand about a player, a team, a club, you can not be sure that your bet will help you win.
Basically the word says it all, bet/ gamble, nothing can be sure with it. It's mostly decided by probability even in sports.
Obviously nobody can be sure of a bet and that goes with everything and not only betting.
It's all about probability and while luck based games relies purely on luck, sports games rely on luck as well as skill.
If you have sufficient information about the team, match, playing conditions then your chances will automatically be higher on the winning side.
Yet there won't be any "assurity" but the probability will increase I believe.