Whatsapp Riddle: The Famous Elevator Puzzle

This one is an old Riddle but still has it’s charm and is really tough for those who do not know this.
A man who lives on the tenth floor takes the elevator down to the first floor every morning and goes to work. In the evening, when he comes back; on a rainy day, or if there are other people in the elevator, he goes to his floor directly. Otherwise, he goes to the seventh floor and walks up three flights of stairs to his apartment.
Can you explain why?
Answer to the Elevator Puzzle
The man is of a short stature. So he cannot reach the upper elevator buttons. On rainy days as he carries an umbrella he can reach and push the buttons.