Sexual harassers, their apologists, the silence of their colleagues, and those who doubt their victims all work together to strengthen systemic/institutional sexism. These are not independent phenomena, but interworking pieces of a powerful machinery that systematically devalues women and their work, and artificially inflates the value of men and their intellectual contributions. You don't even have to think to get caught up in it. That's the nature of systemic *isms. Doing nothing enforces them. Only by consciously working against them can their effects be mitigated.
The toxic cycle of abuse, fear, denial and silence around sexual harassment in academia is described in detail by Janet Stemwedel (@DocFreeride) in her excellent (as usual) Forbes piece about the Marcy scandal.
h/t Renée for this very illustrative cartoon: