Taking over a network takes real money: renting or buying enough computing power to outrun everyone else. Pick a chain and how long the attack runs, from a minute to a day, to see the bill.
Reading live hash rates and prices…
1 minute1 day
Four proof-of-work chains, from Bitcoin's scale down to Kaspa's, plus two proof-of-stake chains, so the same dollar math covers both kinds of attack.
Attacking Bitcoin for one hour would cost about
$0
Buying this much hash power or stake on the open market would push its own price up as you buy it, the way any large purchase does in a market with finite depth. That effect is real and it is not in the figure above: the number shown is a floor, not an estimate of the true cost, and how large that markup would run at this scale is not something this page can source.