Your anecdote doesn't really seem feasible for most people. Do you think it's reasonable that someone who has been out of work for 6 months would take on the risk and cost of flying to a tradeshow?
Come on, now. He's not saying "just fly to a trade show and you'll get job offers," he's saying that you need to be proactive. Go into a business unsolicited and ask if they're hiring (obviously you should know what they do and know that you're a fit).
Are you a web developer? I live in a rural area and there are a half dozen shops within a 30 minute drive. Show up during business hours, ask for the GM or owner and tell them why you're there. Sure, you'll have the people who are put off by you just showing up, but it's just as likely you'll hit someone with a need just a few days (or hours) before they were about to place a listing.
So no, he's not saying to "take on the risk and cost of flying to a trade show," he's saying to be proactive and act like you actually want to have that job, not just a job.
By the way this is one of the things I tell people about dating as well.
You have more chance going to a bar to find a date (where some could be put off by your approach - I mean who cares you only need one person!) then you have sitting at your house expecting someone will knock on your door or come falling through the roof!
Also as is true with any situation where you are only looking for one taker (dating, jobs) as opposed to multiple takers (making sales every day of the same product (encyclopedias?)) you can afford to put much more effort in because it's not something you are going to have to repeat every day. So if it takes 4 weeks of cold calling and you get a job it's a solution to a problem.
First, people who read hacker news are not "most people".
But more importantly "most people" live hand to mouth or have living arrangements that are on the fringe of what they can afford or are only a short time period away from hot having enough money to pay the mortgage.
The idea is to live your life in a way that you have the money to do something like this if you need to do it.
Almost impossible to say of course without knowing the specific person or not whether they should gamble the $1000 (arbitrary) that it might take to take this chance.
Note I also said that I had pre arranged a few interviews and contacts before making the trip.
