Creating the feeling of scarcity invokes an emotional reaction. Let's just picture the following situation:
"Five minutes!", my mom shouted. "We're out the door in 5 minutes!"
It was my brother's wedding day and everyone was in a mad rush. The worst part was that my sister was hogging the bathroom and I hadn't even taken a shower yet.
That 5-minute warning gave me a feeling of "Hurry, hurry, hurry!" This is an emotional response that gives a feeling of urgency.
And this is exactly the feeling that a coundown timer creates on your website. It grabs the visitor's attention by saying, "You only have a limited time until this is possibly lost forever" - and this is the power of scarcity marketing.
A timer gets hesitant visitors to take action. More action means more people buying your product. This is why timers are crucial.