Because If you lose the bet, you will lose all of your money. On the contrary, you may be able to spread out your risk and win some of your bets even if you lose some if you place several smaller bets.

That being said, I only wager what I can afford to lose because I'm a cautious bettor. I have learned to keep on course and that it's best to have a minimum and maximum amount that you can bet, even though there are moments when I go over my limit because of tension I experience when playing.

There might be a tendency that we chase losses and make impulsive decisions. Sometimes it is great to discipline ourselves first.

Same answer as number 3