Yes, it is hackable but the thing is, it would take tremendous effort and resources so it might not be profitable for the hacker. Hacking a private key for example would take a ridiculously long time. They also need to compromise at least 51% of the hash rate in the world and that is almost laughable as one need to own thousands of supercomputers first to even make a dent.
51% has to do with adding a transaction to a block-chain, and once a new transaction has 51% consensus it stays and the longest blockchain wins the battle on the de-centralized network.
This HAS NOTHING to do with security, SATOSHI created "51%" to solve the double spending problem.
Now security, which is what we're talking here, is that there is a KEY, a private key and a public key, your address is public, and if I KNOW your Private KEY then YOUR Money is MINE.
Now that question to be asked about "HACKING BTC", is HOW do I get YOUR BTC private key?
Well it can be done, and above I explained how its done, and if you google, you can learn.
On the question of infinite time and hash-power that's not true, while true on 'brute force' ( dumb search ), a sophisticated sorted butter-fly algo can drop the search space to 2**32, current 'infinite bullshit' is 2**50, or 2**128, but advanced researchers who study EDCSA see patterns and figure out algos to reduce the search space to 2**32 or less, and then it can be done in short-time computationally.
The problem as shown on this topic and OP, is that the majority here don't have a clue about BTC or how it really works.
The OP asked a good question, but the normal BOTS&TROLLS stepped forward with the normal canned bullshit, sure in a world of MORONS BTC can't be broken, that was the idea behind "Brain Wallet", and all the lemmings that followed that moron lost their BTC.
Just a few years ago RSA with 128 bits was impossible to break, but then one day a guy discovered they were seeding with ports which were 2**10, which meant that if you search a small seed-space you could break the CRYPTO in a few minutes to this day BANKS still use RSA, which is well understood how to hack.
Same with BTC ( sha256 ), smart people study patterns and figure out how to reduce the search space so that a crypto-puzzle can be quickly solved.
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All of this is BULLSHIT really because anytime BTC wishes they can move from SHA-256 to SHA-1024 and make BTC impossible to break, IMHO the ASSHOLE hold BTC back to SHA256, because the ASSHOLES want to be able Steal "asset forfeiture" as they wish, just like they do now with banks.
Ergo if BTC doesn't get off its ass, then the zcoin ( zencash ), ... will be where the crypto-anarchy people go, and BTC will be for assholes & morons.