[dllthomas]

If you treat it as a gamble, you can look at expected value (to determine whether it makes sense to play at all) and something like the Kelly Criteria (though my understanding is that it doesn't apply directly) to determine how much it makes sense to be betting. All of that, as Paul said, must be adjusted for your personal risk preferences as determined by your personality and situation, and you should keep in mind that your assessment of the odds is likely wrong (or you should be a VC).