Lots of people tend to look up to celebrities and some can be role models because they are famous and want to set a good example. Some celebrities tweet about being kind or helping others to spread positivity because they know a lot of people will see and will listen to them because they are their role model and are famous. But some celebrities are not very good role models for younger people because they might not really care about setting a good example and just want to be famous for the money, but that is not true for all celebrities, some use their fame for good and spread positivity. It just depends on the person. (Hope I could help) :)