How dare you! 

You have to right-click your bet to collect your winnings.  When you hit a mine you lose your initial bet plus any winnings so far.

This makes the game really bad value.  Every dig gives 20% of your (bet+winnings) to the house on average.  That's 7.4 times worse for the player than playing roulette, which only takes 2.7% of your bet each spin on average.