Why Quantum Computers Are Regarded as One of the Biggest Long-Term Threats to Bitcoin
As we all know, the world of cryptocurrencies is one of the fastest-changing in existence. The prices of cryptocurrencies and their fluctuations depend on geopolitics, macroeconomic shifts, regulatory decisions, technological breakthroughs, and sometimes even a single tweet from the right person.
This particularly applies to Bitcoin, and even more so. According to Fundstrat co-founder Tom Lee, quantum computers might be a genuine threat to this cryptocurrency, and he believes that threat could arrive sooner than most people expect, potentially as early as 2028 or 2029.
What Tom Lee Said and Why It Matters
Tom Lee is not someone who carelessly throws out warnings. He is one of the most well-known and closely followed voices in the crypto and financial world. When he speaks, the market listens.
During a recent interview, Lee pointed to the rapid pace of development in quantum computing and suggested that the technology could eventually become powerful enough to break certain parts of Bitcoin’s existing security framework.
Lee also made an interesting comparison, suggesting that Ethereum and Solana may be better positioned to adapt quickly to quantum threats. That comment alone raised eyebrows across the Bitcoin community, where many developers and long-term holders believe Bitcoin’s design is more resilient than critics give it credit for. Still, the fact that someone of Lee’s standing is raising this issue publicly means it deserves a serious look.
How Bitcoin’s Security Actually Works
To understand the quantum threat, you first need to understand how Bitcoin keeps your funds safe. Bitcoin does not use traditional password-based encryption the way a bank account does. Instead, it relies on something called digital signatures.
When you send Bitcoin, you prove you own it by signing the transaction with a private key, a long, randomly generated number that only you possess. Nobody can fake that signature without having the private key itself.
Adam Back, one of Bitcoin’s earliest contributors and the creator of Hashcash, a technology that directly influenced Bitcoin’s proof-of-work system, pushed back on Lee’s framing. Back explained that Bitcoin seed phrases are protected by an astronomically large amount of randomness. The number of possible combinations is so vast that even the most powerful computers available today could not guess a private key in billions of years. Quantum computers, as they exist right now, are nowhere near capable of changing that reality.
The Real Vulnerability: Older Bitcoin Wallets
Here is where things get genuinely interesting, and a little concerning. While modern Bitcoin wallets are designed with strong protections, older wallet addresses carry a specific vulnerability that quantum computing could one day exploit.
When Bitcoin is spent from certain older-style addresses, the public key becomes visible on the blockchain. That public key is essentially a mathematical derivation of your private key.
A quantum computer running Shor’s algorithm could theoretically reverse that mathematical relationship, working backward from the public key to figure out the private key. If that ever becomes possible at scale, anyone holding Bitcoin in an old, exposed address could be at serious risk of having their funds stolen. Researchers estimate that between 30% and 35% of all existing Bitcoin (roughly 7 million in BTC) is held in addresses that fall into this vulnerable category. That is an enormous amount of value sitting in potentially exposed wallets.
Modern wallets handle this by generating a fresh address every time you receive Bitcoin, which means the public key is never exposed until the moment a transaction is made, and by then, the coins have already moved. It is a simple but effective layer of protection that older wallets simply did not have built in.
Does the Bitcoin Network Have Time to Prepare?
The honest answer is yes, but the window is not unlimited. Quantum computers powerful enough to run Shor’s algorithm at the scale required to attack Bitcoin do not exist today. The machines currently available, while impressive in controlled research environments, are nowhere close to the level needed to break real-world cryptographic systems. Most experts agree that meaningful quantum threats to Bitcoin are still years away.
That said, the Bitcoin development community is not sitting still. Conversations about quantum-resistant cryptography (security methods specifically designed to withstand quantum attacks) are already happening at a serious level across the broader blockchain and cybersecurity world.
The good news is that Bitcoin’s protocol can be upgraded. It has been upgraded before, and it can be again. The challenge is coordination: getting the global Bitcoin community to agree on and implement changes before a threat becomes urgent is no small task.
Other blockchain networks are also working on this problem. The fact that multiple ecosystems are treating quantum computing as a future priority rather than a distant fantasy is telling in itself. The industry as a whole is starting to take the long view.
What This Means for Regular Bitcoin Holders Right Now
For the average person holding Bitcoin today, there is no need to panic. Your coins are safe. If you are using a modern, reputable wallet that generates new addresses for each transaction, your exposure to the quantum threat is minimal under current conditions. The risk is real, but it is a long-term structural challenge, not something that will impact your portfolio tomorrow or next year.
What is worth doing right now is staying informed. Follow developments in both quantum computing research and Bitcoin’s protocol discussions. If you happen to hold coins in very old wallet addresses that have never been moved, it may be worth consulting the Bitcoin developer community’s updated guidance on best practices for securing those funds over the coming years.
Tom Lee’s warning is ultimately valuable, even if the timeline he suggests is debated. The conversation that has reignited is healthy for the ecosystem. Bitcoin has survived existential debates before (about scalability, energy use, and regulation) and emerged stronger each time. The quantum computing challenge is real, the stakes are high, but the community has both the awareness and the technical capability to meet it head-on before it becomes a crisis.