pelf, n. money or riches thought of as bad or degrading. Probably about 1375, stolen goods, property, riches; borrowed through Anglo-French pelf, old French pelfre booty, spoils,of unknown origin (compare Medieval Latin pelfa, pelfra stolen or forfeited goods, possibly a latinization of old French); related to pilfer. The meaning of money or riches, thought of as bad, is first recorded in Dunbar's Poems (1500-20)

Chambers etymology

Pelf - pelt - fur ? perhaps

or illgotten gains????
dieter