Sounds like they're volunteers, not employees: https://forums.dropbox.com/topic.php?id=97303&page=2#pos...
On a side note, why the heck does dropbox have volunteers running their support forum? At this stage, cost savings isn't worth the reputation hit.
If I had to guess - I'd suspect three or four "nines" of their customer support workload comes from their "free tier" non-customers. (Having said that, there's evidence upthread in these HN discussions saying they're also dropping the support ball for paying, even team-account-sized paying customers - that's not OK...)