arrivistes

/ER0 AY1 V IH0 S T S/
noun
  1. 1

    An upstart or newcomer; nouveau riche; parvenu; an ambitious, brash or arrogant person who has yet to integrate with his or her new social group.

Source: https://en.wiktionary.org/wiki/arriviste, https://en.wiktionary.org/wiki/arrivistes