If you had made a 99-to-1 bet for $1 that there’d be an earthquake in Phoenix and then there was one, you’d win $99. High odds yield a high payout.
If that feels backwards to you, don’t feel bad. I found it confusing too—so much so that I consulted with a mathematician to make sure I was getting it right.
Odds and probability are not the same thing
Mathematically, odds and probability are not the same thing. A high probability does mean that something is more likely to happen. But colloquially, outside the world of mathematics, many people treat odds and probability as the same thing. [...]
‘High odds’ and ‘low odds’ are confusing
The problem is that the phrases “high odds” and “low odds” are confusing. When you talk about odds being high, your reader can interpret that as meaning that something is likely or unlikely. The same goes with calling odds “low.”
What should you say?
To be clear in your writing, to make sure everyone understands what you mean, it’s better to describe the likelihood of something happening in a different way. Instead of saying the odds are high or low, you can say there's a “good chance” or a “high probability” of something happening if you mean it's likely. And if you must use odds, it’s better to say they are good or bad, instead of high or low.