Research on the convergence of gaming and gambling has been around since the 1990s. The emergence of loot boxes in video games in the mid 2010s, a game mechanic with a chance-based outcome that shares structural and psychological similarities to gambling, caused public controversy and lead to the inception of a new field of study, loot box research. Since then, various studies have found a relationship between loot box engagement and problem gambling as well as problem gaming. Due to the cross-sectional nature of this data, however, inferences about causality are limited. While loot box research has extensively investigated the relationship between loot box engagement and problem behaviour, little research has been done to explain the underlying motivations of players that drive them to interact with loot boxes. The goal of this thesis is to provide possible explanations for the relationship between loot box engagement and problem gamblers or problem gamers. In doing so, it draws upon two prominent psychological theories. Self-Determination Theory and the Dualistic Model of Passion. Self-Determination Theory's concept of psychological needs and their satisfaction or frustration is hereby used to explain the development of harmonious or obsessive passions, which are introduced in the Dualistic Model of Passion. These obsessive passions have been shown to be possible antecedents of behavioural addictions, such as problem gambling or problem gaming. Thus, the interplay between needs, passions and loot box opening could elucidate the aforementioned correlations between loot box engagement and problem behaviour. However, further research, especially utilising longitudinal data, is needed to better understand these processes.