I don't believe it exists in the Rad Fem sense of 'something to be overthrown'. It is a modern societal construct used to explain the unequal treatment of men and women. It does not exist in the way that say a Dictatorship, Government or Club or other defined group does and therefore cannot be 'overthrown'.
As a societal construct, it can be changed, but as we are all, male or female inevitably part of society and therefore part of that social construct, it can only be changed from within by correcting the inequalities that lead us to construct the idea in the first place.
Inequality in the workplace, under-punishment of sexual violence against women, attitudes that make many believe that DV is acceptable and therefore punish it less than other types of violence etc etc - these things are real and can be 'overthrown' but 'Patriarchy' is just an umbrella label.
To say 'I blame the patriarchy' or 'It's Patriarchy's fault' as if it is something that exists externally to the person saying it also seems faintly ridiculous to me. You may as well just say 'I blame society' or 'It's society's fault' and we can hardly overthrow society, but we can change it.
The patriarchy is not to blame for inequality, people are - men for their sense of entitlement and superiority, women for putting up with it. Most are not even aware of the subject positions they inhabit. You can't 'overthrow the patriarchy', you can change people and attitudes.
(This is why, although I want all the same things as feminists in terms of equality for women, better rape conviction and punishment, improved attitudes towards violence against women etc, I do not call myself a feminist because I just don't view the idea of patriarchy in the same way that seems to be so central to mainstream feminist ideology)