Cute, but with something like a legal defense or a ballot initiative, where a warchest of a given size could swing an outcome, hitting the fundraising goal could be incentive enough to kick in.
Here's the classic college example: in California it costs 1-2 million dollars to pay for the signature-gathering to get an initiative on the ballot. Would 100k college students pay $20 to get, say, 'hot issue' on the ballot? You only pay $20 if the full amount is collected. For 100 million you might have a 'sure thing' campaign, could you get 1 million people effected by 'hot issue' to pay $100?
How much does it cost to get a patent invalidated, assuming a patent reeking of frivolousness should thereby have grounds for invalidation?