Generally I will bet when I get a good prediction based on my own research, for example a meeting between the two teams in football and I will see the chances of winning first before deciding to bet.
Chance of winning alone is definitely not enough and is probably the main reason why so many people lose money. What you need to be looking at is the relation of payout rate to the chance of winning (Expected Value of the bet). So what if the team A has 90% chance of winning if the odds are set at x1.05. This wouldn't be a good bet to make. And if the team B has only 10% chance of winning, but the odds are set at x15.0 - that'd be a good value bet.
Finding a value and deciding where to place your money is really tough. If it's just base from the odd maybe there are more gamblers who can easily assess and manage it and take more money out from the bookies, but in reality it's not. There are more losers the very reason why we keep on seeing more bookies / sports betting that being introduced and keeps of attracting gamblers to use the service.
You need to have that good control inside you, and the right knowledge to guide you in pinking the right game that fits to your understanding.