Can anybody ie upcoming artist make money selling paintings or is it only famous artists whose work sells?
Yes. Very many younger and not yet famous artists sell their work and make some sort of income (although not usually enough to live on). Even moderately well-known artists often have to teach or supplement their incomes in one way or another. Relatively few artists actually make a living from their art, it’s a lousy way to get rich but that’s not why we do it.