While the candidate with the plurality wins, the system is "rigged" in that only certain candidates have a chance at that. Our two-party system is the rigged bullshit part. Some of us consider the two parties essentially the same thing. And yes, I do vote third party.
If you consider the two major parties the same thing, then you simply are not paying attention.
That the two parties are not polar opposites is not surprising, they have to occupy the middle ground to appeal to the greatest number of voters. That doesn't in any way shape or form mean they are the same thing. I trust that most readers can offer multiple examples of real differences between the Democrats and Republicans (and other parties) I'll offer just three, to make the point.
One party is in favor of health care for all Americans. One is not. One party is in favor of women receiving equal pay for equal work. One is not. One is against gay marriage, the other favors recognizing it. These strike me as real differences. I don't see how the major parties are "the same". (Which is not to say they have nothing in common and that they aren't close to each other on some issues)
This is just flat out false. In a theoretical world, "thinking matters" and money would be irrelevant. Since most people won't think, your thinking is irrelevant. Thus money plays the dominant role in our politics.
Most people do think. People are incredibly smart animals. As a species we do a lot of thinking. What you mean is most people don't think the same as you, which means you have to persuade them. Damn. It's easier just to throw up your hands and say it's all rigged. (Might as well use that excuse not to invest in stocks too)
You use coke as an example, but clearly money in advertising like that matters - billions are spent on it because it works. Ditto in politics. Clearly money in politics matters.
Clearly it only works for people who are willing to buy a Coke. I've reached a place where I'm unwilling to put the stuff in my body. It doesn't work on me, nor do Pepsi's ads. I simply will not drink soda anymore.
In politics I'm not going to be persuaded by an add. I'm not going to vote for one party because most (though not necessarily all) of it's ideas are repugnant to me. No amount of spending is going to change that.
Study Finds US Is an Oligarchy, Not a Democracy
We already knew from 12th grade govt. class that the US is not a Democracy. It's a representative republic. I'll agree it has Oligarchic elements to it but the question is what are you (and the rest of us) going to do about it? The answer is to vote for a candidate closer (but not exactly on the mark) to your ideals. You can quickly google the main candidates and get their "views" and this costs very little, almost nothing. After that ads only work on those who won't inform themselves.
I can't choose between current Pentagon spending and slashing the Pentagon budget by 95%. Rather, I can (pretend to) choose that by voting for a third party candidate that has no chance of winning, but realistically, I can choose between current spending and a reduction of 3-5%. The new "lower" spending becomes the new normal, (if my party wins) and I continue to optimize by continuing to vote for slight reductions, even though I'll never see a sensible defense budget in my lifetime.
This representative republic thing is a real bitch; others get to voice their opinions too, and vote for candidates that you (and I) don't necessarily agree with completely, or even to a very great extent. It's much easier to say it's all rigged, or to vote 3rd party and pretend you're principled. Politics comes down to making unhappy imperfect choices. Focus on what's (in your opinion) the best (least objectionable) party, with an actual chance of winning, and vote that way.
We live in an age of social media. Ideas spread like wildfire. Traditional ways of persuading voters are not as effective. Traditional campaign methods are not as effective. Thinking is what matters.