As blockchain technology has evolved, it has introduced an array of functionalities and mechanisms. However, this advancement has also attracted a growing number of threats specifically targeting blockchains, heightening concerns regarding blockchain security. Although several researchers have attempted to categorize blockchain attacks in their respective studies, there remains a significant disparity among these taxonomies. This paper delves into three distinct classification methodologies, comparing their respective strengths and weaknesses. Additionally, it offers insights into the essential attributes that a comprehensive and effective taxonomy should possess. By breaking down each classification method, the paper provides a clearer understanding of how various researchers approach the challenge of categorizing blockchain threats. This includes looking at the criteria each method uses, such as the level of technical sophistication required for each attack, the potential damage inflicted, or the underlying motivations of the attackers. Furthermore, the paper emphasizes the importance of a universally accepted taxonomy, as this would not only facilitate more effective communication among researchers but also help in devising better defense mechanisms. In conclusion, by analyzing and comparing these classification methodologies, the study hopes to pave the way for a more unified and comprehensive approach to understanding blockchain security threats in the future.