Could it be expressed as a success rate?
So a win rate of 2 wins out of 5 becomes a 40% win rate. Profit / Loss can still be shown but one big odds win still out performs consistent winning bets.
Or drill down further and show number of games covered and the success rate. For example one of us may ĥave had 2 entries but no profit whilst selecting 4 out of 5 correct results. Ìt is still an 80% prediction success rate. A person picking 3 teams each week with 2 correct trebles and a complete wipeout in the third week has a nice profit but only has a successful prediction rate of 6/9 or 66%.
You can get your leaderboards to show different results to show there is something for everyone.
I learned an important thing working in a bookies call centre. Bookies hate singles. There are less variables with singles. The more selections the more variables there are and even at odds of 1/4 or 1/5 a line of 10 "certainties" is not a safe bet. Too many variables. Only takes one player sent off or one shock result and you win nothing. But of course if you are betting always keep it fun.