MSport is certified by the NLRC. That should assure that you are in safe hands. Crosscheck the URL multiple times to ensure you are on the real betting website: After the online survey, check the Uniform Resource Location properly before clicking on it. For MSport, the right URL is msport.
Therefore, the maximum number of wins expected for 1000 people with odds of 1 to 20 is 50. So, first of all, 1 to 20 odds is actually equivalent to 1 in 21 people winning, not 1 in 20 people winning.
When you see the odds presented as 30:1 or 3:1 that's actually just showing the payout for a winning bet, not the likelihood of that team winning. 30:1 doesn't mean that the team is 30x more likely to win, it means that if you bet on that team and they win you will receive $30 for every dollar you bet.