Such stories are very inspiring! But as you know, these are isolated cases in a million.
Yes, but if you keep trying, it you could be one of the lucky winners that will be listed in the history. 
And you seem to understand that it is almost impossible to win such a large amount with a small bet, but this 1% inspires and you think, maybe this time it will be me?
Almost impossible is not impossible, so as long as there's a chance, people will still gamble, if they could buy a lottery ticket, why can't they bet on sports doing parlay if they love sports betting.