[wdpk]

The technology (preventing double spending) only works if the amount of computational power in the hands of a single agent is always less than 50% (or preferably a little bit less) of the total network power. If the condition is not met, someone could first pay you 100 bitcoins for say a Tesla then spend the same 100 bitcoins on something else (say cocaine...). If the proof of work becomes "easy" for a single agent then her view of the ledger is the ledger. So the value would very quickly go to 0 USD regardless of any aesthetic pleasure one may derive from a bunch of bits

[landemva]

The system prevents a usable attempt at mining a double spend because of the validating nodes. Your reference to having overwhelming hash power would be for a reorg attempt, which has it's own challenges to successfully implement.