Other people's money
About
The phrase other people's money is commonly used in two ironically contrasting ways.
Finance Usage
The original usage, which was common as early as 1914, referred to the investment banking industry. In his book Other People's Money And How the Bankers Use It (Wikipedia), Louis Brandeis (who became a Supreme Court Associate Justice two years later) sharply criticized the often-destructive uses to which investment bankers put the money entrusted to them.
This usage resurfaced, in slightly modified form, in the 1991 fictional movie Other People's Money (Wikipedia), whose main characters include financial con-men.
Thatcherian Usage
A more recent usage was coined by British Prime Minister Margaret Thatcher in a 1976 television interview:
Socialist governments traditionally do make a financial mess. They always run out of other people's money. It's quite a characteristic of them.
The phrase in this sense has become widely used as a criticism of "socialist" policies, even those promoting social welfare within a capitalist framework. The argument implicit in such usage is that social welfare programs serve only to take money from those who have it and give it away to others who then squander it, eventually depleting the original source, and do not otherwise benefit society.
Ironic Justaposition
The Thatcherian usage is ironic in that the phrase is being used in support of capitalism versus "socialist" programs intended to do social good, while the original usage was criticizing the excesses of capitalistic practices and the harm they do in the name of profit.