Pay attention to the words.
Fewer people buying stocks than selling.
The amount of stocks "bought and sold" are the same, the amount of people is not.
If what you are saying is true, stocks would always be at the same price since the amount of stock bought and sold are the same!
If one day there are 100 people that want to buy the stock, and the next day there are 10 people interested, the prices will fall.
If one day there are 100 people that want to buy the stock, and the next day there are 10 people interested, the prices will fall.