Computers are very vulnerable in many ways.
The problem is our dependency on them. Our society and economy would collapse dramatically if the computers that run it failed.
The great Belgian historian Henri Pirenne proposed that the real collapse of economy of the Western Roman Empire didn’t come until the Moslems over-ran Egypt. That cut off the supply of papyrus, which destroyed the commercial network, which depended on paper for record-keeping and communications. The so-called Dark Ages were dark because nobody could write anything down. They could use parchment, but prepared sheepskins were so scarce and costly that they were often scraped clean and recycled. The word palimpsest was coined for such documents; that’s how common the practice was. It wasn’t until Europeans learned to make paper from linen rags that things picked up again.