How do the actions and decisions of people effect change?

If you really think about it, we all follow what other people do and decide. If a new trend of a certain designer clothes goes around, in weeks everyone in your school is wearing the same thing. Brunelleschi was considered a crazy person as he told his plan to build a humongous dome with no scaffolding. At this time it had never been done and even the thought of that was extremely insane. But Brunelleschi would not give up. He came back and asked the people to stand an egg on its narrow end and no one could. Brunelleschi simply cracked the bottom of the egg and there was their dome with no scaffolding. In 1436 the dome was finished and a new error started. People started thinking outside the box, exploring new things. Just like a trend, one day something starts and in months it is going around the world. Fillipo Brunelleschi made a decision and acted out and did effect people and that was when the "Renaissance" started to really occur.