Women are in the exact same position you are in, with the added disadvantage of being women
This is your assumption. You are assuming that the men going to the event are average men, which on average are more likely to be employed in tech. I don't think that's true in this case, I think it's mostly desperate people, possibly also from marginalized groups. Looking at the video I see mostly foreigners, possibly in need of a visa to not be kicked out of the country. Keep in mind they paid 600 bucks for a super tiny chance (imagine what are the chances that recruiters at that event will not ignore them because they went there to recruit women).
Also, reading a bit online it seems that there is always been a percentage of men attending that event.
I will not address the last paragraph, your suggestion of what "this proves" is completely arbitrary and prejudicial, I won't say what that proves, instead.
I would say that if you have the concrete power of organizing an event with tens of thousands of people and huge sponsors, you might have some power and are less marginalized. Possibly (and I mean possibly) this is not the case for the average men who attended that event? If this is true, then I don't see why it couldn't be possible to help each other, using the power obtained (with years of struggle and effort).
Ultimately, you do need exactly that kind of solidarity and reciprocal recognition to be able to join the fight against the top.
Also, in this case "helping" is also very generous. Those people paid 600$ for basically nothing. The chances that recruiters who joined the event will care for anything else than recruiting women (to boost diversity in their company) are extremely little.
Either way, I still don't understand what the alternative is. For example, if you are a foreigner who needs a job for your visa, the chances that you will have a) a network of people, b) the resources and c) the overall possibility to organize something similar are nonexisting. What is our proposal for this people? How do we ensure that we can fight the top, if workers are splitting among themselves? I am asking genuinely, because for example, in my opinion, if today you go to some of those guys and you say "sorry, fuck off this is not for you go do your fair", tomorrow, in the workplace it's not going to be as easy to build a union with your woman colleague. It's going to be easier to see yourselves as part of two different groups than the same class.
So what can we do instead that leaves the necessary space for women while not alienating this people?