The limitations of classical computing in solving complex problems in cryptography, materials science, and optimization necessitate the development of a new computational paradigm based on the principles of quantum mechanics. This article aims to analyse the current state of quantum computing hardware, evaluate the primary challenges to achieving fault tolerance, and project a realistic timeline for its practical application. The methodology involves a systematic review and comparative analysis of publicly available empirical data from peer-reviewed literature and corporate technical roadmaps, employing a framework of key performance indicators such as coherence times, gate fidelities, and qubit counts to assess leading qubit modalities, including superconducting circuits, trapped ions, and photonic systems. The analysis confirms that while superconducting qubits currently lead in scalability, with demonstrations of quantum supremacy using 53-qubit processors, trapped ion platforms maintain a significant advantage in gate fidelity and coherence times. The central finding identifies decoherence and high error rates as the fundamental barriers, necessitating that current Noisy Intermediate-Scale Quantum (NISQ) devices rely on error mitigation techniques rather than robust quantum error correction. The comparative assessment concludes that no single qubit modality yet fulfils all DiVincenzo criteria for fault tolerance simultaneously. The path to scalable quantum computing is shown to depend on the successful implementation of topological error-correcting codes like the surface code, which currently requires thousands of physical qubits to create a single stable logical qubit. Projections based on current progress suggest that while demonstrations of quantum utility on specific problems are imminent, fully fault-tolerant quantum computers capable of breaking RSA encryption or revolutionizing drug discovery remain a long-term endeavour, likely requiring several more decades of intensive research and development. The practical value of this research lies in its synthesized technical overview, which provides a clear, evidence-based roadmap for researchers, engineers, and policymakers to navigate the technological hurdles and strategic investments required to realize the transformative potential of quantum computing.