I have never liked live betting because I believe the results are unreal as the matches are played and unless I have so much funds to spend or loose that day, I see it as a perfect waste of good money.
If you are betting before the start of the match then you will get a lot of better odds as compared if you bet on a match after it has been started.
As everything has some disadvantages and advantages the cons of betting for the matches before the match starts that you are just making a random guess and you do not know which team will win hence the bet can go all against you in this case.
The advantage you have with the lower odds if you place the bet after the match starts that you know that which team is winning so even though the profit you will get will be less but the probability of winning that bet increases a lot.