Is it possible to 'crack' a hash with brute force?

Question

Hashing

Suppose that after 100 years, mankind was able to brute force a 65-character hashed (sha-256) string. *Theoretically, this is possible, since a complete search will require ~1.7*10^69 gigabytes of free space*.
Let's return to the theory. It turns out that I can hash the hash (pun intended) (sha256(sha256)) + 1 character and then decrypt it. And this means that I can also hash the hash + 1 character almost an infinite number of times (well, it’s clear that it’s not infinite, but a very large number, let’s say ~ 1.7*10**69 times), which means with each operation, I will 'win' 1 byte of information, which means that in the end I will be able to compress 10s, 100s, 1000s, etc. terabytes of data into one 64-character string.
(Small clarification: I take the string 'defabc', hash to -> 'abcdef' (6 characters) I take abcdef (past hash) and the 7th byte of the data I need to compress (let's say '1') = 'abcdef' + '1' -> '618281' and so on until I get a hash of all the characters I need to compress, and then 'unpack' the hash from '618281' into 'abcdef1' in the opposite direction, take '1' and write into a variable, take the 'abcdef' hash, etc...
My question(s) is(are) if one day mankind can 'crack' the hash, will I be able to send a picture to a friend using only 64 bytes of traffic? Let's say I create a rainbow table that can 'crack' hashes with a 70% chance, how long will it take to look up such a table? but I can not refute, what do you think?

Answer 1

which means that in the end I will be able to compress 10s, 100s, 1000s, etc. of terabytes of data into one 64-character string.

almost right... Only you mixed up everything in your head...
This is called data compaction (the algorithm is similar, but works a little differently), but the distribution density will stop you before you reach the 64-character line.

then in the opposite direction 'unpack' the hash from '618281' to 'abcdef1'

Only if the hash is a compaction. Otherwise - no.
Direct answer to your question: in order to transfer something whole in the minimum volume, it is necessary that this minimum volume with the highest percentage probability correspond to the transmitted data.
And this means that we need a trained neuron with a database of objects (from the sender and recipient, or centralized) to extract them after finding the highest degree of probability.

Answer 2

The hash cannot be decrypted.
You can choose a huge variety of options that fit the hash. But which of these options is correct - you will never know.