The situation are a bit different though. The Bay Area is competitive despite its housing market, while Berlin to a large extent is competitive because of its housing market. If rents become similar to other major European cities Berlin will lose a lot of its appeal and potential compared to those other cities.

Silicon Valley became what it is today because there was cheap industrial land for chip fabs and random startups.

Debatable. As far as I know it wasn't really until around 2000 that Silicon Valley became dominate enough to really set it apart from other regional technology centers like Dallas, Boston or Pittsburgh.

In any case that doesn't really help Berlin if it takes, say, five years for its housing market to catch up to its European neighbors.

What? You're overlooking an enormous number of factors.

If it's cheap industrial land alone that made Silicon Valley how did Texas, Nevada, The Midwest and other places miss out on a tech business boom?

Texas has TI which is a big tech firm.