While I initially agree with you and can understand your view point based on your previous experience, I think there are two categories of tech: -Business Value Add -Hype / Marketing
I separate these out because we've already gone through a terrible economic downturn that is sputtering to produce jobs and yet we see an explosion of jobs in the tech sector. That's because of the value add software that is reducing the number of employees, paperwork or steps in a process a business needs in order to operate.
Those types of companies are going to be fine through another economic downturn because their clients have realized how much their saving by using the software. These value add tech businesses may see a slow down, but not a collapse.
The biggest example that is here to stay is E-Commerce. Look at how many companies / businesses are realizing how much easier / cheaper it is to go online than build a brick and mortar store with employees, rent, utilities, taxes, repairs, maintenance, etc.
Even some apps are here to stay. AirBNB, for example, is a personal value add when I'm traveling. I have no problem paying them a couple dollars to reduce my overall travel costs by 15-30%.
What will collapse almost overnight are the apps, websites, etc that are simply fluffy websites, marketing materials, or buggy unusable software.
My thought is stick with the people helping other people make or save money, and you'll be safe through the next one.