10 to the power of 25 years, while the universe is only 13.8 billion years old. Specifically: The most powerful quantum computer currently has less than 100 logical qubits. Cracking BTC's SHA-256 would require about 2330 qubits, which is over 20 times more. If a breakthrough does happen in the future, around 35% of BTC's supply (including Satoshi's 1 million coins) could be at risk. Of course, the key point isn't 'whether quantum will come,' but 'whether BTC will upgrade to quantum-resistant encryption before it does.' For now, time seems to be on BTC's side.