I will be spending at least 130,000 hours (very likely more!) preparing for or working on my career. Here, I define career rather loosely not to mean any particular job or industry but rather work I will do throughout my life (which is roughly waking time - personal time). It naturally follows that I should spend a decent amount of thought trying to find the adequate direction in which I wish to expend this time.
The two primary reasons why people choose to do what they do are passion and money. Some choose to be a musician because they are "passionate" about music while others go into investment banking (and increasingly, quant) for the six-figure salary. The problem with the general advice to do what you are "passionate" about or what will make you the most money is that the causal relationship is often inverted.
Does doing what you are passionate about lead to a good career, or does a good career lead to passion? Passion often develops from a sense that you are good at what you do (or at least can become good at it) and what you are doing is worth doing. Both seem like requirements any good career must satisfy. Hence, I believe any good career will automatically lead to you becoming passionate about what you do. Trying to make a career from what you are currently passionate about might lead to the trap of confusing the topic and the content.
The other, and probably much stronger for the "hoop-jumping" community I am part of, reason is money. Again, though, I think the relationship is somewhat inverted. Money, simply, is a claim on other people's time and resources. When you have money, you can exchange it for things other people made or did. So when you earn money, someone valued what you did enough to give you claims on their own future time and resources (or the collective pool of such claims in the economy).
Why does a quant firm pay a 22 year old $300,000? Not out of the goodness of their hearts. They pay that much because if they don't, someone else will. Your salary is roughly the minimum amount a firm needs to pay to keep you from leaving. It is determined by how scarce and replaceable you are in the labor market, not by how much good your work does or how meaningful it is. This makes income a poor primary signal for deciding what to do with your career.
This is not to say income does not matter. It does. But it is a means, not an end. The right way to think about it, I think, is as a floor: figure out how much you actually need to live the way you want to live, make sure your career clears that bar, and then optimize for other things.
But I think there is a third reason, one that people rarely admit to, that is probably the strongest driver of all, at least in the world I inhabit as a Columbia student. That reason is prestige. People do what they do to maintain or increase their perceived social standing. This is especially visible in the finance-heavy majors and increasingly in the entrepreneurship crowd as well. The problem is that prestige as an end goal leads to infinite recursion: prestigious high school leads to prestigious college leads to prestigious job leads to... what exactly? There is no terminal state. You just keep chasing the next prestigious thing because the only use of prestige is to acquire more prestige.
Prestige does have some real utility: it affects first impressions and can open doors. But it is essentially only valuable to people you have not yet met. Among people who actually know you and your work, it quickly becomes irrelevant. Building a career around the opinions of strangers you haven't met yet seems like a strange way to spend 130,000 hours.
So if passion, income, and prestige are all poor primary goals, the question becomes: what should I actually be optimizing for? That is what I am trying to figure out.