Only what I think is that he can go for 10 odds instead of going for over 100 odds. But if he is betting with just $3, that is a good bet because $3 is an amount of money that someone can be able to lose.
If he is gambling on a single match, know that he might be tempted to use high amount of money and which I can not advise him to do but he can reduce the parley bet to like 10 odds.
The odds of 10 are not a small odds either, but you are right that I will not bet a lot of money on such a parlay, so this can save you from big losses on one bet. And a single bet with a small odds can make you believe that the favorite will easily beat the underdog and you will be ready to bet a lot, but no bet will give you a guarantee of winning and if you lose a lot of money on one bet it will be much worse than if you make several bets with odds of 10 but with a small bet, and if such a bet plays at least once, it can cover many losing attempts.