I don't disagree that the level of risk is different, or even that the level of risk is within, say, an order of magnitude. There's no doubt that some founders risk more (in some cases, much more) than employees. Wouldn't argue otherwise.

However, I would caution you that "racking up debt" isn't something only founders have as a risk. What you've described in your second paragraph is where just about anybody who isn't rich or well connected and has to rack up debt going to college finds himself, at least in the US. I would also caution you that employees frequently cannot merely walk out the door of the failed start up and into a paycheck across the street (as it were). They have to spend time, and their own savings, looking for work, in most places.

Compounding this is that odds are said founder has accumulated something the fresh college graduate or now former-employee hasn't: connections and the ability leverage his 'failure' into lucrative employment or future business opportunities. This helps mitigate the risk significantly.

I would argue that within the Valley your second paragraph actually isn't true. I've found that most people coming out of startups have a very easy time finding a job, unless they choose not to (i.e. they start their own business, etc.). I can't speak to other locales.

There are many places where tech startups exist that aren't the Valley. I've lived in both places. Outside of the Valley I've never had a job search take less than two months (time to offer from start of search); most often it took four to six months. I haven't had to search for a job in the Valley yet, so I'll have to defer to the experience of those who have.

That's why you start the search when you don't need it, yet.

Who's to say you will need it?

If nothing else, an outside alternative improves your negotiation power within the company.