Your vote does not have a fixed value. The value of your vote varies by three different metrics: the first is the SP you possess, the second is the weight of the available VP you assign it, and the third is how depleted your VP is from casting votes,, or becomes during the vote window as you cast votes thereafter. Another issue is that some folks have even more variables they consider prior to voting, such as curation rewards. Some people only vote because they get paid. This is already a nebulous target, because it depends on who besides you votes how hard and when they do so.

I'm not even going into circle jerks, purchased votes, or promoted posts, and how this might complicate them.

Most people have but little idea of how to calculate the third variable, and even for those that do know how, the work to do so if not often undertaken. I don't undertake it at all, and just always vote at 25%, because I have discovered that if I vote at that weight, I generally remain within VP that can recharge in ~1 day, which maximizes the VP I have to vote with.

Finally, I have to agree with @lextenebris on one thing: voting is already too complex (witness my rule of thumb regarding vote weights) and this would make it more complex. I do not agree that people don't vote at all due to lack of robust comprehension. I observe that even idiots express opinions, or vote, despite demonstrable complete lack of comprehension of relevant issues and consequences, so reckon very few people actually even vote less when incompetent to do so rationally and well.