I like your ambiguous use of 'they'. :)

Any theories as to why? Whatever the truth is, it's even more important to understand why something is a certain way.

A few guesses as to factors:

1. Some prominent people are libertarians, and outspoken about it (Peter Thiel, Jeff Bezos, Eric Raymond, etc.), so the ideas are circulating in the community.

2. This part of the economy is doing well, and as a result techies have little personal incentive to support any alternatives to free-marketeering. We generally have options and can get away with telling our employers where to stick it, if we don't like their policies, without the result being poverty. Being in an "employees' market" where we have substantial leverage insulates us from many of the less enjoyable aspects of market economics. In a few situations where this doesn't hold, e.g. the issue around health insurance for small startups in the U.S., I think you do see considerable defection from the otherwise pro-market views (health reform was popular in the Valley).

I put it down to experience. It sounds great, until you actually try to live it for a lengthy period. Ayn Rand, after all, eventually collected social security.

Was she a hypocrite for buying from state-run food depots when she lived in the Soviet Union, as well? Are free market advocates now obligated to starve themselves before taking money out of a system they were forced to pay into? That's quite a stacked deck of cards you're arguing with.

According to The Fountainhead, yes!

Observable reality and pointing out logical inconsistencies (hypocrisy) are generally considered fair game.

Truisms that assume the very thing under debate are generally considered not useful in moving a discussion forward.

The argument being that Ayn Rand paid into social security, and was therefore entitled.

Ayn Rand was not a Libertarian.