Button wrote: Perhaps it's more a question of managing punters' bets...
Precisely. The 'bookmaker' doesn't have a view on who might win. All he is doing (nowadays using computers - though my grandfather had to do it on paper) is adjusting the odds so that the money from losing punters is greater than the payout to winning ones.
In days of old with small time bookies at racecourses this would sometimes require him to put money on an outcome with another bookmaker to 'offset his bets'.
It's all maths basically.
The fact that the 'bookies are usually right' relies on the 'wisdom of crowds' though this can obviously be skewed by a large individual bet or bets on a particular outcome.