be rolling

be rolling in it

To be exceptionally wealthy. "It" refers to money, with the image being that of one literally rolling around in piles of cash. I hear her father is rolling in it, so I wouldn't be too worried about her future. Once we get this plan underway, we'll be rolling in it in no time!
See also: roll

be rolling (in it or in money)

be very rich. informal
Rolling in (i.e. ‘turning over and over in’) here has the sense of ‘luxuriating in’. The idea of wallowing in riches has been current since the late 16th century.
See also: roll