In my opinion SA bookies have a death wish, no financial backing or both. They generally put up totally unrealistic markets and get scared off by small bets.
If punters refused en masse to bet with them until they had reasonably competitive markets, no more than 115% they would have 2 options:
1. Close up shop and find another job.
2. Start acting like proper bookmakers and put up decent prices.

They are so far managing to make a living due to punter ignorance about basic stats.
In a market of 140% it is quite likely every bet is a losing bet, even though of course there is a winner in the race. It's the fact that something will win the race that tempts ignorant/uninformed punters to take poor odds in their search for the winner.