But if you start up knowing full well that the only path to success is 
    through acquisition (that is the idea, on its own, cannot be used to build a 
    sustainable, going concern), then you're simply gambling and contributing to 
    the speculative bubble that is the Valley.

I disagree. Startups, these days, is how corporate R&D is performed. Yeah, it's easy to look at the most prominent startups and say that it's all froth. But there are a surprising number of hardware and software startups that are trying to tackle problems in hardware and biology. Very few of these startups have an exit strategy that involves becoming a public company. It's all about developing a viable product (not necessarily a viable business), and then shopping the company out to potential acquirers.