A brute force attack to guess a BIP 39 seed phrase is currently computationally infeasible and would require an astronomically long time to succeed, primarily due to the vast number of possibilities (10^39 for a 12-word phrase) and limitations in existing computing hardware.
"at the moment the type of computing power that we have would take an astronomically long time due to two factors the first is the length of the seed phrase as we said earlier it would take 10 to the power of 39 guesses which is a huge number in computational power the second is the limitation of our Hardware to make these guesses"
