Betting on politics on PredictIt. I wouldn’t recommend it as an income stream, but having an interest in probability, markets, and international politics, it has taught me to read the news more objectively.
The problem with such predictions (likewise stock market) is that they are not binary. The question is not if a stock goes up or down. The question is "when?". There is no such thing as "opposite" of a date (in a useful sense).
There is actually another questions "how much?". There is also no opposite for that.
But many predictions ARE basically binary. I made so much money on the "Will Trump be impeached by the end of 2019?" question. I can't believe how many people put money on that.
To be honest, I’m still down from the 2016 election. After taking a break from it, I’ve started to recover since taking the time to sit down and understand the rules, fee structure, and betting tactically at the beginning of this year. Even if I were to attribute all my luck this year to skill and I could keep it up, I wouldn’t be able to make a minimum wage at it. I was particularly leaning on OP’s word possibly :)