How about
sum(df[next_col] - df[curr_col] for curr_col, next_col in zip(df.columns, df.columns[1:]))
Test everything in a Python shell (iPython, Azure Notebook, etc.)
- Someone gave you an advice you liked? Test it - maybe the advice was actually bad.
- Someone gave you an advice you think is bad? Test it before arguing - maybe it was good.
- You posted a claim that something you did not test works? Be prepared to eat your hat.