[craigyk]

At any point since bitcoin's inception there have been plenty of major govts that could have easily afforded the resources to pull off a 51% attack.

[gritzko]

A real bad thing here is the asymmetry. To prevent 51%, the network has to burn enormous amounts of energy 24x7 forever while the attacker only needs his energy for the duration of the attack.

[lukifer]

Counterpoint: physical security largely works this way too.

[gritzko]

Well, things work much better in crypto (not proof-of-work, but the "real" one).

[sanswork]

And now a single company can. Progress!

[cgjaro]

It has always been the case that a single company could 51%-attack the network. No regression here. In fact the cost has continually increased over time. So, yes, progress.