Psychology of scarcity as a motor for sales and investments. The human mind reacts strongly to scarcity. Products or opportunities presented as rare trigger a sense of urgency. In business, campaigns with limited vacancies or stocks are clear examples of this strategy. In the investment market, IPOs, emerging cryptocurrency or exclusive funds arouse desire for the simple fact that they are not available to everyone. However, scarcity can also be dangerous, leading to impulsive decisions. The real strategy is to use scarcity ethically, balancing the psychological power of the "little available" with rational analyses of real value. So businessmen and investors can harness the mental trigger without becoming his victims.