This contradicts your more sophisticated argument that we cannot plan and predict mass change (you will probably wish to substitute that with "revolution") (the flip argument is in fact the case: the cost to you for pulling the lever is so minimal that it is not even worth the effort to carry out the calculations of the effects). The best things in these matters, IMHO, is to follow the Hindu idea of 'dharma' and do your bit without expectation of instant gratification. Now, if you believe (as you have hinted -- or explicitly stated? -- in the past) that voting for a Dem is in fact a bad thing, that it goes against your sense of duty, then you should not do that of course.
--ravi