The answer is: Fascists usually gain power after a country's economic collapse.
After an economic collapse, people in the country most likely experience some sort of fear for their uncertain future. In such situation, people subconsciously desire strong leaderships to get them out of the bad situation.
The fascists government create the persona of a 'strong' leadership due to intense use of military power. Even though the leaders of a fascist group are complete dictators, most people willing to overlook it during desperate situations.
