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You're actually right to see the difficulty in calculating daily loss probabilities however it's kinda like a moving target when you don't even know how many bets you'll place. Actually your math on the 5 loss streak (62 bets for 2.00 odds 45 for 1.90) makes sense as a theoretical average for those chains to actually pop up.
But, and this is the big 'but' horse racing doesn't really play like a coin toss. The idea of no chain if there aren't enough bets left in a day or how one stable's results influence subsequent odds kinda proves that actual betting is far more dynamic than simple statistics.
This is because you're actually not just flipping a coin but you're playing a game where the odds and probabilities are constantly shifting based on actual events which is why those losing chains don't just appear on calculation. luck can't really be predicted.