1929 was caused by excess credit issuance. True, that the gold standard was in place, but the spirit to keep credit in check was not. The federal reserve already existed, so this excess was made possible by their control of credit.
Bubbles are only bad if people are deceived, because the proper way of riding a bust out by doing nothing (creative destruction) is too painful and may lead to political extremism.
https://www.brookings.edu/blog/ben-bernanke/2016/01/07/the-d...