I remember how much stress I had during some games on which I had $100 or $150 on - even though it's not really a huge amount of money and I'll make it back at work in a matter of a few hours so losing it doesn't mean that much it still put plenty of stress on me. Nowadays I have $20 or $30 on a game it's not much of a stress, and I probably have a better hit rate since I changed my tactics! Almost got a 14/1 bet on Netherlands yesterday too only to lose because the amount of cards didn't click.Playing for fun is far better. Whenever I have tried to be calculative, I have lost. But recently I have just had a look over the teams and the matches and bet instinctively, and have incidentally started turning over profits, and have stayed away from the dicey matches. And as of today, I am in the plus, albeit small, but still.
As others have said, singles and at most doubles is the best way. Long shots bets hardly ever come off.
This World Cup is too good to be spoiled by bold $150 losing bets that but a damper on a game.