Last year, I started following an on-line tipster in Canada. My reasoning that as much as he thought of himself as a handicapper/sports advisor, my analysis on his betting is that he's simply a gambler.
His staking I found remarkable. When betting odds on, he wagers enough to win a point (he says $100.00). Example: -128, he wagers $128 to win $100.
Betting underdogs, he wagers a point. Example: +155, he wagers $100 to win $155
I remember years ago visiting a U.S. betting site. Minimum wager was $10.00. And when I clicked on to place a bet (i.e. -120), my wager became $12.00 and I couldn't make it $10.00.
It seems to me that this is a bookmakers dream to have punters think this way and top up their bets with 'the juice'. The mentality of a "sure thing" means betting more, almost telling the punter that 'if you want a piece of the winnings, you have to pay for it"