If I am (say) 70% favourite to win a bet and I know that if I win the bet I'm going to be paid 2:1, then obviously the bigger the bet, the bigger the payout. How do I make the bet bigger- I raise and re-raise to get as much money in there as possible.

The point of the above blurb is that when you have the best of it, your profit is directly related to the amount of money you can get others to commit.

There are of course, other reasons to re-raise

Regards,
Ian