Adjusting for inflation, "Gone with the Wind" (1939) has made the most money. In today's dollars: $1,454,721,307.
Hancock
Supposably Johnny Depp has made the most money. He made $55 Million for the Pirates of the Carribean The Search for the Black Pearl in 2007.
Documentary film making.
Titanic
Highest grossing film is Titanic.
My answer to your question is that home alone made the most money because it got 6 Oscars and sold out the night it first appeared in theaters.
Titanic probably or Schindler's List
It Was The Lion King.
Either avatar or the rise of the trolls
The original Star Wars movies were the most profitable series of movies. Star Wars brought in a total of $797,900,000 worldwide.
Most larger budget films go to Cinema because of their potential to make money and their fan base. Really, its thanks to Cinema that big films can be made, as their are too many risks involved just releasing a 12million dollar film on DVD, which people may not buy. Also, cinema is an experience, as you are far more likely to go out with friends to the cinema than to go watch a DVD with mates. The main stars wouldn't be to happy on a DVD for all their hard work either. Unless your Steven Segal.
It is likely impossible to say which film was "watched" the most. But as far as highest grossing films, which are films who made the most money in the theaters due to the amount of money people spent on seeing them, they fall in this order: Avatar, Released 2009 made $2.7 Billion Titanic, Released 1997 made $1.8 Billion Lord of the Rings, Return of the King, Released 2003 made $1.1 Billion