The objective of a security program is to mitigate risks. Mitigating risks does not mean eliminating them; it means reducing them to an acceptable level. To make sure your security controls are effectively controlling the risks in your environment, you need to anticipate what kinds of incidents may occur. You also need to identify what you are trying to protect, and from whom. That’s where risk analysis, threat definition, and vulnerability analysis come in. What is being protected? What are the threats? And where are the weaknesses that may be exploited?
Spending more money on security than an asset is worth rarely makes sense, but by the same token, spending nothing at all to secure an asset makes no sense ...