Why? Because writers have a skewed perspective when it comes to facing the odds. Odds make us laugh. The bigger the odds against us, the more easily we ignore them. We persevere. Like this:
Because it's next to impossible for someone to have the imagination necessary to dream up a story, with loveable, realistic characters who overcome impossible odds... without having some of that overlap into real life. To read hundreds and thousands of books showcasing successful dreamers without internalizing the power of dreams.
Reality might bite, but it can also be ignored. For those who ignore it long enough, and who work faithfully to accomplish the improbable... sometimes reality conforms to match what we think it ought to be.
So what impossible goals do you have?