'rightfully-earned' originates from the combination of 'rightfully' and 'earned'. 'Rightfully' comes from 'right', which has Old English origins, specifically the word 'riht', meaning 'just' or 'lawful'. 'Earned' comes from Old English 'earnian', meaning 'to deserve' or 'to merit'.

'Rightfully' evolved from Old English 'rihtlice', and 'earned' from 'earnian', eventually forming the modern English compound adjective 'rightfully-earned'.

Initially, 'rightfully' meant 'in a just manner', and 'earned' meant 'to deserve'. Together, they have maintained the meaning of 'deservedly obtained'.