A more economical version of the same thing is to engage in honest mining through several front companies that together have 51%. Until a strategic opportunity presents itself and they start colluding.

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api 4 days ago | parent [-]

Sure, and this is well within the capabilities of any competent large intelligence agency.

It's only a secure system if adversaries are either small or economically rational.

	▲	ifwinterco 4 days ago \| parent [-]
		For monero and other smaller chains maybe, but for BTC this is already at the point of being quite difficult (the intelligence agency really would have to be quite large). The money is one thing, you also have to somehow acquire a huge % of the ASIC supply over years, and the not insignificant amount of energy to run them