An politician from the Republic of Ireland said in 2014 before the Brexit vote -
If ever Northern Ireland could to become a more economic wasteland than it is, it would be if Britain were to leave the union.
From another source -
Economically & strategically, Northern Ireland holds no value to the UK. Mr Brooke's carefully considered statement is as true now as it was then. Indeed, with regard to the public finances, it is a something of a drain on the British exchequer - to the tune of several billion pounds.