opportunist

As nouns the difference between opportunist and optimist

is that opportunist is someone who takes advantage of any opportunity to advance his own situation, placing expediency above principle while optimist is a person who expects a favourable outcome.

As nouns the difference between profiteer and opportunist

is that profiteer is (pejorative) one who makes an unreasonable profit not justified by cost or risk while opportunist is opportunist.

As a verb profiteer

is to make an unreasonable profit not justified by cost or risk.

As nouns the difference between philanthropist and opportunist

is that philanthropist is a person who loves humankind in general while opportunist is opportunist.

As nouns the difference between opportunist and expedient

is that opportunist is someone who takes advantage of any opportunity to advance his own situation, placing expediency above principle while expedient is a method or means for achieving a particular result, especially when direct or efficient; a resource.

As an adjective expedient is

simple, easy, or quick; convenient.