They're already on the one big island... they've just decided not to worry about the other big island across the sea yet because the one they're on is big enough for the time being.
I think I'd use the term 'putting it off for later'. Almost like technical debt. I'd probably look more seriously at GDPR compliance at about the same time I start working on internationalization and localization.
These are things I can put off until later, I don't need them to validate my startup concept. If the startup is successful, it might make sense to expand the market.
Considering Facebook even actively tracks non-users, where's the "users" choice of not participating in that glorious Silicon Valley invention?
As far as I can tell, the "user" doesn't have a whole lot of choice there and Facebook isn't the only company doing that kind of aggregated data collection.
I'd agree with that if Facebook would be that single outlier nobody wants to emulate.
But Silicon Valley isn't a monolith where everybody is on the same page about everything, I have no doubt there's plenty of people in SC who consider FB a success-model to be followed into a shining future.