You are correct when you say that Many people join and leave Steemit every day. They come and go for many different reasons. There are many folks here that only follow the super popular content creators but also there is a very dedicated group of individuals that will go and make welcome the new Steemians as well. In fact, one of the best ways to gain new followers is to go to the #introduceyourself section and comment on the Posts there. Be honest and welcoming. I find that it is not unusual that I might gain 5 to ten followers just by making a few heartfelt comments.