An outsider who seeks power or success presumptuously WordNet 3.0 & Open English WordNet

In the history of the United States, carpetbagger is a largely historical term used by Southerners to describe opportunistic Northerners who came to the Southern states after the American Civil War, who were perceived to be exploiting the local populace for their own financial, political, and/or social gain. Wikipedia

Derogatory term for Northerners who moved to the South after the Civil War Wikidata

An immigrant from the Northern to the Southern States after the American Civil War of 1861–5, especially one who went South to gain political influence. Wiktionary