Starting a startup and failing doesn't look bad in your CV, don't worry about that. But if you are looking for a job, you should definitely work on your technical skills, learn new technologies etc instead of your networking skills...
Spent 3 years becoming an expert in technology X? Even if the whole job offer is about X, you'll have only slightly better chances than the guy who had a glimpse at X 3 years ago - the interview process simply has no way to find out how much better you are at X.
But if you were at a final round with a few other qualified candidates (maybe better qualified than you, maybe worse qualified - noone can tell, they can only tell that they're qualified) - and you're 'the grumpy one' or someone else has a good emotional contact - then that will be a decisive factor. Even if the decisionmakers deny this; and even if the decisionmakers are informed about such biases and actively try to counter them - research shows that they still do decide that way, it's simply human to do so.
Completely stupid irrelevant factors (such as being taller) do have a relationship to the offers you get and how much people are willing to pay you. That's how life works; ignoring it won't change it; denying it won't change it; saying that it's not fair (it isn't) won't change it - you may just learn about it and try to exploit it. And 'work on your "being a guy that a CTO would want to have a beer with" skill' is solid advice on how to try to exploit how reality really works.
Conversely, if you're a self-motivated learner, a good team member, and able to contribute, but don't quite have the technical skills we're looking for, we'll gladly take a training hit (usually 2 to 4 weeks) to get you up to speed on language X in exchange for an engaged and valuable employee.
But that might just be my company.
But """work on your "being a guy that a CTO would want to have a beer with" skills. That, combined with a bit of networking"""
Just sounds terribly wrong.
Drinking beer with me after work or good out together in the weekend isn't one of the requirements.
Shameless plug: Any companies like this, feel free to contact me through the email address in my profile. :-)
It may be if you consider that the CTO would probably like to talk about interesting technologies, new programming language developments etc. over that beer. In other words, getting genuinely interested in your occupation will go a long way when looking for a job.