The comment up this thread holds true: human attention is not evenly distributed. That doesn't mean, however, that there's an imperative to "network" or build a "personal brand" – plenty of people gain a deep satisfaction from excelling at their craft.
If "make it big" just means a giant pile of money, there are plenty of millionaire pure technologists at Silicon Valley companies whos names are never told; the thousand or so that were created when Google IPO'd are basically unknown. Forbes had a recent article advertising Craigslist competitors, but reading between the lines, Craigslist has minted some of them, but they're entirely nameless among the wider population. If thats your definition of "making it big", then it's possible, but if you want broader recognition, I don't know that it's possible.
Maybe I'm being unimaginative, but outside of Steve Wozniak I can't think of any pure-technologists with household name recognition. The closest that comes to mind is Elon Musk, but unfortunately for you, there's plenty of marketing going on. I'd bet a large number of readers even here won't even recognize the name Vint Cerf.
Maybe you feel marketing is about lying, maybe selling yourself feels icky. However they're skills like any other; refusing to learn and use them would be like refusing to learn or use multiplication.
Read Sam Altman's praise of Greg (gdb) (http://blog.samaltman.com/greg) who is quite the gifted technologist, but the praise is for his dedication, on both technical and non-technical talent.
EDIT: Not saying these celebrities don't also earn their keep through their skills. It's just disappointing how much of a factor self-promotion is.
In a valley of smart and motivated people, discoverability will always be a challenge...though I don't doubt it's much more competitive now than ever.
There area millions of quiet, confident, competent people across industries. People who reliably turn out high-quality products and are well-paid for their work. They get on well with their colleagues and progress with their career at a decent pace. You just don't hear about this much. Doesn't this count as making it?
I'd say that the reason you hear more about people who are well-known is essentially just because they are well-known :)