Yep it is correct.

You've got to think of laying like backing VERY short priced horses to win. In this case you were risking $20 to make $5. That's the same as backing a horse @ 1.25!

Or perhaps an easier way to think of it is like this...if you had a 10 horse race where every horse was the same chance of winning then by backing a single horse you would have 10% chance of winning and a 90% chance of losing (9 other horses could beat it). If you lay a single horse, then you have a 90% chance of winning and 10% chance of losing. So you are essentially backing the 9 other horses in the race.

Hence why the return is low. But if you can find a high strike rate (in relation to the odds you lay at) then there is money to be made!