At some point, Dropbox clearly didn't take security seriously. They claim otherwise now. The question is now "at what point should we believe them?" It's subjective and my opinion is that the 2011 management that didn't take security seriously then probably still doesn't take it that seriously now - they've simply hired underlings to worry about it.
I have experiences with companies that have security in their DNA from day one, and I've {observed, worked with, been a customer of} a whole fuckton more who bolt it on later once time and money permit. Most of the latter do not actually care one whit about security, it's just one more "avoid existential threat x" box they have to tick as their business grows.
Google falls into the former. Dropbox and Slack and LinkedIn fall into the latter.
https://www.troyhunt.com/we-take-security-seriously-otherwis...
There is no reasonable amount of time that needs to pass until I willingly let a Dropbox or a Slack or a LinkedIn run code in my workstation's kernel. Maybe that makes me a jerk - if it does, I apologize.
PS: That's not how you spell my username.