An excellent explanation from Dan Roberts of the Telegraph:
"Imagine you took your pay cheque down to the bookies each month and put it all on the 2.15pm at Newmarket. Imagine, too, that you were lucky enough to win - not just occasionally, but every month for several years.
With your income soaring, you might start to behave as if you had secured a permanent pay rise. You would want to reward yourself with treats and bonuses to celebrate your good judgment. You might start to bet on horses with longer odds.
After a while, you would probably cease describing it as gambling and start believing you had invented a new paradigm that others were simply too stupid to notice.
Now, imagine the moment this dream turns sour: the day you start losing not just the monthly flutter but your underlying source of income too. Imagine the humiliation you might feel as the secret of your immense wealth vanishes before your eyes.
Imagine demanding that your less fortunate friends and neighbours bail you out by giving you some of their pay cheque instead."