Trezor is well designed and certainly better than using a PC, even an off-line PC with air gap. But it is not 100% safe. I already explained how a criminal can get around its safety features, by using social engineering or fake malicious hardware. The fact that people keep denying those risks only makes those risks more significant.
@JorgeStolfi: doomsday again? Please give us a break, will you?
Your repeated and repeated and repeated comments only makes you more ... well... less significant.
BTW: I am old enough to remember the Year 2000 bug - millions of $$$ worldwide went into trying to fix it - but at the end... it was only a big IT
FUD... Are you from that generation JorgeStolfi?
No, sorry, I was busy at Troy, desperately trying to warn my compatriots that that Greek horse could be a trojan horse. But they just told me to stop spreading FUD and fuck off.
The Y2K bug was not a disaster because, thanks to the harping by the FUDsters, it was mostly fixed or hacked around in time. How can you tell that it was pointless FUD and waste of money?
Unfortunately, 95% of people cannot believe that a real risk can happen until they see it happening. The other 5% are dismissed as paranoids and FUDsters before it happens, and quickly forgotten afterwards. One could fill volumes with cases where warnings by "FUDsters" were ignored, and then the disaster happened much worse than their worst case scenarios. See Fukushima.
The BCI debacle was caused by a bug accidentally introduced in the javascript that people downloaded to generate the keys and sign the transactions. The bug was fixed after a few hours, but even so it affected hundreds of people and allowed the "theft" of more than 500 BTC -- fortunately, most of them by a "benevolent thief" who returned them to BCI. In fact, the extent of the damage is still not known precisely, more compromised accounts are still being found.
The BCI javascript was open source, and the buggy version was duly posted on github. It was not discovered by looking at the code, but because the "benevolent thief" was continuosly monitring the blockchain for certain type of weak signatures, and started seeing many of them. The programmer who committed the bug acted irresponsably, but apparently within his normal privileges and habits. Couldn't it have happened with the Trezor firmware instead of the BCI javascript?
Now imagine a criminal aiming his skill and resources to expliting that type of attack...