It’s for similar reasons that many people hate members of the “other”. The same reasons that some women hate men, the same reasons some white people hate black peoples, the same reason some Pakistani hate Indians, the same reason some tenants hate landlords, the same reason gangs hate members of other gangs…
They blame them for their problems, usually without basis but with sufficient foundation to convince themselves (or be convinced by others) that it’s a fair blame.
Some men hate women because they blame women for their place in society - this is the premise of incel culture. Men are only respected in life if they are what women find attractive - almost no unattractive men are successful. That creates a bizarre chicken-and-egg style narrative where some men think that if women found them attractive then they would be successful (rather than the, more likely, reality that if they were successful then women would find them attractive). They then blame women for not finding them attractive - if women changed then their life would be better. That’s the crux of it really.
In addition, with increased equality and autonomy, women are taking from men what used to be theirs. The best jobs, the best opportunities, housework-free lives, childcare-free lives etc - all of that has been stripped away by women establishing themselves as equal. Some men don’t like that. Some men find that their lives are harder because of it.
Their attitudes are obviously wrong, but it’s not hard to see how they’ve either ignorantly convinced themselves into that belief or been manipulated by others into thinking that way. These men hate women because if we prioritised their desires over our own then their life would be better - they view us as powerful and uncaring and they completely fail to recognise that we’re entitled to prioritise our happiness over theirs.