It's worth a try at least

Certainly. I suspect I wouldn't have blinked if you said 'an effective'.

if it works then I've achieved my immediate goal and still have all the money.

That's true. But you don't have the time and energy which constitute the opportunity cost. Those could, of course, have been spent making more money or getting laid. But who knows, often evangelizing a cause helps the latter goal rather effectively as well! Or so Robin would have me believe.