If you only have $20k and need $0.5M for an urgent life saving operation, then the expected payoff for not playing is -$20k (death) and it's -$20k+(some non-negative value representing the win) for spending all of your money on tickets.
To answer your specific question, Srivastava called the provincial lottery agency (iirc - it was Canadian) and asked 1) Would they send him a large number of tickets to use for a promotion / fundraiser, and 2) Would they "buy back" at face value any unused tickets. They said they would gladly do both - meaning he could examine before scratching, return unscratched, and also avoid lining up at the drug store to buy 10,000 tic-tac-toe tickets at once!
Edit: Previous discussions
Srivastava - http://news.ycombinator.com/item?id=2166555 Cash WinFall - http://news.ycombinator.com/item?id=2828122
I give Srivastava credit for finding and exploiting the loophole, but they also seem to be easily closable. So the scratchoff is vulnerable. Future ones might be as well. A little common sense and better security could avoid another mishap.