Hack Bitcoin is a vague phrase.

Hack a Bitcoin wallet software, hack a Bitcoin wallet, hack a website that provides online wallet, paper wallet, attack the Bitcoin network. What did you mean about hack Bitcoin?

About network attack, Bitcoin network has very high hashrate, very decentralized and risk to have such attacks is very slim.

• How many Bitcoin confirmations is enough?
• More important, if an attacker does such an attack, Bitcoin price will be dumped to the hell and even the attacker will not get much money from it.

Practice with Bitcoin confirmation risk calculators

• https://web.archive.org/web/20181231045818/https://people.xiph.org/~greg/attack_success.html
• https://jlopp.github.io/bitcoin-confirmation-risk-calculator/