the treaty of versailles was viewed as unfair. after wwi, germany and its allies were forced to pay huge sums of money, reduce their militaries to almost nothing, and give back territory they had conquered.
germany couldn’t pay the debts, they were out of money and the people were suffering. when hitler came, he said he would reclaim territory that rightfully belonged to germany, modernize the military, and get the country back on its feet. to the german people, that seemed very promising (keep in mind this was in the thirties before atrocities committed by the nazi party came to light)
mussolini had similar tactics as hitler, promising better things for the country. more stability, a better economy, and simply giving people hope.
it also gave each country goals to work towards. they weren’t just wandering around looking for opportunities. they had a plan and they were going to make it happen. that’s why the citizens of each country put them in charge. hope that helps :D