Depending on what the threat is it can be very beneficial to us. For example, the threat of losing your job can make you work harder. If you work harder you may not lose your job. The threat of getting fat can make you eat better, and so on and so on...
A vaccine works by presenting the human immune system with
an apparent threat. The body then trains itself to overcome a potential enemy.
The stress of weight lifting threatens muscles with weights they cannot lift
repeatedly, and they grow stronger in response. Similarly, the threats a nation
perceives cause it to raise an army, put an intelligence gathering system in
place and make allies abroad. The crisp
threat of fall warns squirrels to store away food for winter. Threats teach us
to prepare—better a threat than a surprise attack.