Why there are odds of 1000?

This question is often ask by some of the inexperienced players. The Match between Everton and WBA, the result is 2:0 for Everton and odds on impossible results are 1000. Only an idiot will bet on it. Wait, it’s not that stupid.
 


We player on 1-0 lay, for the most of our money. There is still lot of time remaining but we would like to play a different match. So we buy the score 1-0 for 4€ (unfortunately it’s the lowest stake possible) 
 

We lose it but we have defrozen our Money and we can play different matches.