Vision 2030 emphasizes the importance of digital transformation, innovation, and sustainability as key drivers of economic and social progress. Building a sustainable 6G is a key element of a sustainable digital infrastructure. Saudi Arabia acknowledges the transformative potential of 6G technology and its impact on evolving sectors such as telecommunications, healthcare, transportation, and smart cities. Toward this end, this paper will study the current status of 6G technology in Saudi Arabia and related factors to develop a sustainable 6G. In the light of the fact that the country is prioritizing privacy and security when designing 6G networks, challenges and limitations for 6G sustainability will be considered in terms of sustainable development goals set by Vision 2030 and the UN Sustainable Development Goals (SDGs). In this context, sustainability requirements will be addressed from two dimensions: The first one is 6G infrastructure design where sustainability requirements are analyzed in terms of energy optimization, AI/ML integration, network slicing, security and privacy, renewable energy sources, and optimal resource utilization. The second one is the economic growth driven by 6G networks and ecosystems where sustainability requirements are analyzed in terms of energy consumption, resource utilization, waste generation and quality of life. The analysis of 6G infrastructure requirements and economic growth led by various 6G-based industries promoting efficient and sustainable practices resulted in a roadmap providing future directions for a sustainable 6G in Saudi Arabia.