Step 1: purchase, borrow, or steal enough hash power to reach 51% for a short while
Step 2: use this power to force enough transactions to make yourself rich enough to keep 51% power indefinitely
Step 3: profit
51% hash power lets you doublespend coins. It does not let you steal from wallets or change the block reward rules.
Which is sufficient to allow you to do what I suggested. Spend coin once on paying for everything, and again on yourself to keep all the money to spend again later.
Re:Bitcoin is fiat money, too
by kazagistar on Saturday September 23, 2017 @11:04AM
(#15320044)
So you become like a government, able to print more currency at will?
Sure a government might do that, but they could point a gun to every full node owners head and tell them to stop it just like China did. It would also be much cheaper.