It's not just a 'wisdom of the crowds' thing where you are using people's betting in aggregate. The odds also reflect private information that other in-the-know

It's not just a 'wisdom of the crowds' thing where you are using people's betting in aggregate. The odds also reflect private information that other in-the-know people may also have. The problem with pool betting (like in HK) is that the odds only become significant right before the start, when everyone has placed their bets. This means that there is a strong motivation for everyone to wait until the last possible moment to bet - meaning that the odds then only become useful even later!