Security isn’t about protecting everything from everything. It’s knowing what you’re protecting from what (and what you’re not protecting). That’s why we use threat models.
An analogy: you don’t protect food from the environment; you protect different types of food from different factors of the environment. You might design a heat lamp to protect the freshness of your dinner but a freezer for your ice cream. What you don’t do is design a heat lamp and assume it’ll protect your ice cream also.