When people say “Bitcoin is unhackable”, I usually think they mean the cryptography. SHA-256, ECDSA, proof-of-work .

But after spending time studying blockchain security, I’ve become convinced of something uncomfortable:
If Bitcoin were ever seriously attacked, the failure wouldn’t start in cryptography.
It would start somewhere far more human.
Bitcoin’s cryptographic foundations are probably the strongest part of the system. Breaking them would require breakthroughs that ripple far beyond Bitcoin , they’d break banks, governments, and the internet itself.

So attackers don’t aim there. They aim at the edges. They aim at incentives, coordination, usability, and trust, the messy parts that can’t be solved with math alone.

One obvious weak point is custody.
Most users don’t hold their own keys. Even many who think they do rely on hardware, backups, passphrases, and assumptions they don’t fully understand. Attacking Bitcoin doesn’t require cracking SHA-256 , it’s often enough to exploit poor key management, social engineering, or custodial concentration.
From a security perspective, that’s not a Bitcoin failure , but from a user perspective, it absolutely feels like one.

Another fragile layer is social consensus.
Bitcoin works because people agree on what Bitcoin is. Which chain is valid. Which rules matter. Which changes are unacceptable. That agreement is informal, social, and slow , and that makes it resilient but not immune.

Confusion, misinformation, regulatory pressure, or rushed changes can fracture consensus faster than any hash collision ever could. Attacking belief and coordination is often cheaper than attacking code.

Then there’s usability.
Security and usability are always in tension. Bitcoin leans heavily toward security , intentionally. But complexity creates room for mistakes. If using Bitcoin safely feels inaccessible to normal users, they’ll outsource responsibility to intermediaries.
And once that happens, the attack surface quietly shifts away from cryptography and toward institutions, interfaces, and trust relationships.

None of this means Bitcoin is weak.
In fact, I’d argue the opposite: Bitcoin survives precisely because it assumes humans are the weakest link and designs conservatively around that fact.

Bitcoin’s real battles are fought in education, UX, incentives, and social coordination , not in hash functions.

So here’s the question I’m genuinely curious about:

Which layer do you think is Bitcoin’s weakest today ; custody, usability, social consensus, regulation, or something else entirely?

I don’t think there’s a single right answer. But I do think that’s where the real security conversation should be happening.