Synonyms for Opportunist:

adj.

all (adjective)
timeserving, opportunistic.

n.

leap at the chance/opportunity/offer, make capital out of something, benefit, get, jump at, exploit, gain, seize an opportunity/chance, take advantage of something, grasp. opportunist (noun)
self-seeker, expedient, timeserving, opportunistic.
person (noun)
self-seeker.
vacillator (noun)
rascal, timeserver, bounder, go-getter, politician, businessperson, carpetbagger, trimmer, Ker, ingrate.

Other synonyms:

rascal, ingrate. self
timeserver.
temporizer
trimmer.
Other relevant words:
ingrate, bounder, Ker, gain, grasp, carpetbagger, get, benefit, go-getter, rascal, businessperson, trimmer, politician, timeserver, exploit.