I guess there's a limitless range of replies to this one; based on everyone's individual experience.
Just as with any career, there'll be good days and bad days. Even good decades and bad.
As for flying, purely and simply, without the utterence of the word "career", the answer is many things. The freedom, the ongoing challenge of something that you'll never perfect, but getting a kick out of it on the odd occasion when you get close. The ability to move in three dimensions and the chance to look down at the world from a different perspective to mean sea level. People crawl over each others' backs for the corner office; in the sky it's a different office every day.
I'm probably biased as I've enjoyed nearly every minute whether living flat broke in a caravan in the bush or sitting in Centrelink after the Ansett collapse, to watching the 'Southern Lights' in the Flight Levels. I posted an article on this very thing not long ago, but here it is again.
So you want to be a pilot? An Aviation Blog by Owen Zupp.
As I said, to each their own and for their own very worthy reasons. This is just my two bob's worth.
Cheers
Owen