Risk

Imposter phenomenon can be a common experience for grad students (and faculty and administrators and human beings). Doing things you haven't done before requires some bravery and some risk taking. But don't be ridiculous about this - like the snowperson above. C'mon Frosty, that's just dang foolish. Even if you pull off roasting that marshmallow, if you eat it, it's going to melt the mouth part of your snowhead. And then most of the rest of you.

This is just one reason why you don't see a lot of snowpeople in grad school. It's not really the main reason, but still...