laugh all the way to the bank

(also, cried all the way to the bank)

Exult in a financial gain from something that had either been derided or thought worthless.

• You may not think much of this comedian, but he's laughing all the way to the bank.

Despite the seeming difference between laugh and cry, the two terms are virtually synonymous, the one with cry being used ironically and laugh straghtforwardly.

.... The American Heritage dictionary of idioms: Google books

cf 1. McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

Fig. to be very happy about money that has been earned by doing something that other people might think is unfair or that they criticized.

• He may not be in the nicest business, but he is doing well and can laugh all the way to the bank.
• She makes tons of money doing what no one else will do and laughs all the way to the bank.

cry all the way to the bank:

Fig. to make a lot of money on something that one ought to be ashamed of.

• Jane: Have you read the new book by that romance novelist? They say it sold a million copies, but it's so badly written that the author ought to be ashamed of herself.
  Alan: I'm sure she's crying all the way to the bank.
• That dreadful movie had no artistic merit. I suppose the people who produced it are crying all the way to the bank.

cf 2. Cambridge Idioms Dictionary

if someone is laughing all the way to the bank, they have made a lot of money very easily, often because someone else has been stupid

• If we don't take this opportunity, you can be sure our competitors will and they'll be laughing all the way to the bank.

cf 3. Cambridge Dictionary of American Idioms

to be pleased about the profit earned from doing something

• Team owners complain about the latest TV deal, but in fact they are laughing all the way to the bank.
• After we sold the house, my wife cried and I laughed all the way to the bank.

... http://idioms.thefreedictionary.com/bank