Student or Learner
Those who smile at you today and you suppose them as fellow,
Will they be by you tomorrow?
They are how nice in good day, but on the run in bad day
Won’t you tingle inside?
I think that the term you are looking for is a fair-weather friend.
(1) fair weather = good weather
(2) There are some people who are your "friends" when the weather
is fair (that is, the sun is shining brightly. In other words, everything
is going well), but when the weather is not fair (that is, it is raining
very hard. In other words, you are having many problems), those