I personally experienced wins placing bets provided by an insider on a few local matches. I didn't spend big, as I wasn't familiar with such a tipster, but the same thing happened as mentioned.
And then you believe that tip, and that person who gave the tip will give you a winning tip again? Actually, you've just been tricked, and the thing that makes you win is not the tip but luck. It was just nothing other than a coincidence. Yes, it happens sometimes, and we made up our minds to think that tipsters are right. They are just effective when it is a manipulated game, but it never works on others. If their tip won't win, they always find an excuse in order for you to say yes and buy again.