Are you in a startup career path or are you one and done?

Strongly recommend, if you're interested in startups as a career, that you add "taking a job at a startup and working your way up to a key role" to your to-do list. I know a couple people who have tried to make startups their career by serially founding go-nowhere companies; that's the wrong way to do it.

(My rule of thumb, which I've back-rationalized onto my career, is not to start back-to-back companies).

I totally agree. The reason this is so important is it makes it possible for you to see the ways companies fail without bearing the burden yourself. (Because, odds are, the startups you join will fail.)

It also shows you that there is more than one path to success. I've worked for several startups and each one taught me a different way of thinking about what are the important things to focus on, what kind of people to hire, and what problems are worth solving.

I think there are lots of ways to go about startups and only some subset qualify as the yegg's "startup career path." Which is to say, there are a fair number of things that are startups and can be done with a couple coders and some ramen over a couple months -- often not evening needing a "marketing" guru -- while there are lots of other problems which require more specialized domain knowledge (either with respect to technology, market, or both).

In this case, what you need to succeed depends largely on having the right set of skills to succeed within your specific domain, assuming you have one. I'm generally of the opinion that there is much lower risk in these areas (assuming you know your market well) since presumably all you have to do is match an existing need with a product, the primary barrier being your competence.

How do you acquire the skills necessary? This too depends on which side of the ball you are on. Larger startups need people in different roles. Rather than getting in on a little startup and being part-time coder, part-time cleaner, part-time ramen cook, get out in the would and be the most excellent in whatever facet you excel in. Heck, you may decide that making the world a better place in whatever capacity you are best at (usually also what you enjoy) you is better than attempting getting superrich and retiring at 30.

In other words, my advice to all "startup" people out there is do what makes you tick, do it as best as you can, and let your startup, if it arises meet a need that you know is real. This may be a problem that people don't realize is a problem (like limited and often unintuitive course management software) or it may be something bigger and better that only a few people will understand (e.g. a cure for Multiple Sclerosis).

Anyways, I've nothing against serial entrepreneurs if that's what makes you tick. More important though is do what you love.

This also has a lot to do with the fact you shouldn't be starting companies if you haven't worked for one before.

The rationale is that if you don't know what the boss looks like to an employee, you won't know what to do as the boss.

I don't know that I'd go that far. It looks like Graham has found plenty of first-time startup workers that have gotten on base.