As somebody who works in the computer game industry, experienced the harassment of GamerGate first hand, and literally works in communications to gamers, yes, I think a lot of men do see gaming as a secret boys club and feel like that is being infringed upon, and I’ve seen many people express just that during the height of GamerGate.
I believe this to the degree that — to this day — I’m still slightly afraid of somebody trying to use my opinions to get me fired from my job. But ultimately we have to decide that we will not be intimidated.
I completely agree with you that there is a distinction between all of those groups. Alt-Right — like all political monikers — does not refer to a uniform group but to a coalition of identities ranging from professional trolls like Milo Yiannopoulos, white nationalists like Richard Spencer, the gamers who harassed people in the name of GamerGate, and (some subset of) the people who voted for Trump.
They have many things in common but they also have many differences. But one thing they all have in common is that their beliefs lie so outside the norm of expression that they warp our communication. Note, this does not mean that their beliefs themselves are what go beyond the pale, but rather how they talk about them openly.
Where a traditional conservative might dogwhistle, somebody from the alt-right would straight up just state. This does not actually mean that they believe those things more strongly (in fact, many elements of the alt-Right are significantly less racist than traditional conservatives). Instead, it merely means that they have a culture of direct expression of unpopular views in opposition to social norms.