great post. i think the main cause is economic / structural, but the underlying problem may well be exacerbated by bad behaviour of individuals. code4lib have an anti-harassment problem to deal with the behavioural problems (https://github.com/code4lib/antiharassment-policy) I've never been to their conferences so couldn't say how helpful it has been for them. as for dealing with the structural issues, that's a bigger problem without any clear answers that I'm aware of.