A Windfall can be defined as an unexpected receipt of money that you have received without budgeting them previously.

The key word here is unexpected because it appears there is no plan what to do with the money and many makes the mistake of wasting them for granted. Consider this for an example:

A tourist had $100 dollars which he treats as an expense for his casino entertainment. He played the Roulette game and placed all his bets on the number "0", having dreamt of the number the previous night. Unexpectedly, the ball drops on the very same number he put his money on and the payout is 42/1, which means he won a total of $4,200 including his original stake. Now, this is a windfall.

Thinking that this windfall is not his money to begin with, he continues playing and ends up losing a couple rounds until he ...