And tomorrow it will be the other way round.
Unless you've discovered some magic bias between +3s and actual off time (and I very much doubt that you have), these things will balance out.
It will be very interesting see the difference over the next several hundred races. I'm guessing your frustration won't be with the size of your profits, it will be with the size of your losses, unless your strategy is a lot more complex than just laying at x-overs. I hope your 500 euro stake was just an example, because that's a pretty big stake for a strategy which is obvioulsy still being tested.