someone who is so ardently devoted to something that it resembles an addiction; "a golf addict"; "a car nut"; "a news junkie"
You can use junkie to refer to someone who is very interested in a particular activity, especially when they spend a lot of time on it. a computer junkie
(Yeni Sözcükler) Colloquially, an adrenaline junkie is somebody who appears addicted to adrenaline. Adrenaline in this case comes from an endogenous source (i.e. the adrenal gland) and does not imply the use of exogenous adrenaline (e.g. injection). The term came into use in 1993. Originally, it was used to describe argumentative people who deliberately (consciously or unconsciously) find excuses to explode in order to get an adrenaline fix. This mode of receiving a fix is deemed just as addictive as a recreational drug (such as heroin, hence the term "junkie"), but perhaps more harmful as it negatively involves other people. The phrase adrenaline junkie was used in the 1991 movie Point Break to describe the "Ex-Presidents."