The past few years have seen an increase in domestic or foreign investors deciding to invest their financial resources in sports, specifically in football clubs. This article aims to determine the profitability of investments in the sports industry, football, and football clubs. To determine the profitability and self-sustainability of large sports systems, it is necessary to analyze the structure of revenues and expenditures to determine the factors and their impact on each segment of the financial structure of the sports organization. The analysis of the structure of the revenue and expenditure sides of the budget will be used to detect the importance of certain factors in sports organization operations. It is known that, in terms of expenditure, there are "less and more costly" sports, that is, sports that can achieve their sports results with lower budgetary expenditures and those sports and competitions that require higher financial sums to achieve their sports goals. Of course, depending on the competition level, revenues and expenses of sports organizations grow. As football is the sport with the most significant number of followers globally, the topic of this paper is precisely football and football clubs, both in the Republic of Croatia and in the most attractive and best football leagues. A comparison of revenue structures will also answer the question of self-sustainability in financial terms. This refers to the analysis of the extent of stable revenues that the football club manages directly, their share in total revenues, how dispersed the revenues are, and the like. The management must answer all these questions to manage the sports organization well.