Assange chose to remain in an embassy for years rather than face questioning (not even a trial) for the offenses alleged against him. Snowden and Manning's leaks endangered the lives of US and foreign military and intelligence personnel, and a number of foreign intelligence personnel were killed after being identified in those leaks.

Yet somehow Epstein and Harvey Weinstein run rampant among our own soil, all with open secrets.

Do you expect the police to just magically know that people are committing crime? The criminal investigation process usually begins with a police report (of someone reporting a crime). In the absence of a police report (as with the Epstein and Weinstein cases) the police have "no cause" to investigate absent some other mechanism that publicly reveals alleged crimes (like a news report). And on that note, in both of the cases you cited, prosecutors did try to investigate the rumors, but couldn't find anyone wiling to testify against those men until the scale of their crimes became public.

Epstein was arrested and awaiting trial once his crimes became publicly known, and before he committed suicide was expected to face charges in multiple states and countries. Epstein became so toxic that multiple men known to have gone to Epstein's parties have faced social and financial repercussions for it. Melinda Gates famously divorced Bill because of his friendship with Epstein. Similarly, Weinstein was also arrested once his crimes became public and is facing charges in multiple states, was kicked out of every industry group, and essentially banished from his former life.