Explanation:

- Be on the breadline generally means struggling financially or barely making ends meet.

- Option 1, Having plenty of money, is incorrect as it suggests wealth, not poverty.

- Option 2, Find a successful way of making money, implies improving financial status, which differs from being on the breadline.

- Option 3, Earn a lot of money very easily, also denotes financial success, the opposite of the idiom's meaning.

- Option 4, Be very poor, is indeed the correct interpretation as it reflects a state of financial hardship or poverty.

Option 4, Be very poor, is the correct answer.