Because the dating market is absolutely brutal towards men. The average male probably gets 1-2 matches on tinder per month. When he sees that, he decides to explore advice on the internet on how to attract women. This leads him eventually to the redpill which is hyped to crush his reality and show him the truth about life. When he half-believes the redpill, he is called a simp or blue pilled. This makes him more deeply embedded into the redpill.

But most men don't recognise this sort of manipulation and go deeper and deeper.

A lot of men especially from MGTOW circles and man hating women actually still want the love of a woman or the opposite sex. But cover up this desire with hate to stop themselves from loving and being hurt again