For some reason, I feel less threatened by a dragonfly than a bird, even though it has the same destructive blade-destroying potential.
You're correct in feeling less threatened by a dragonfly (and incorrect in thinking it has the same blade-destroying potential as a bird). Dragonflies weigh roughly 400 milligrams and are made of soft-body parts (relatively), while even the smaller bird species in your area (a bank swallow, for instance) minimally weigh 18 grams (or 18,000 milligrams - several orders of magnitude higher) and have dense flesh and bones (though they are hollow). Hitting a dragonfly with your Mavic would have not done a thing (maybe a brief blip in the video and a smudge on the blade) and would have been nothing to even alter your flight for. Even a decent-sized bird would probably not have brought your Mavic down.
People grossly over-react to the threat of birds and significantly overestimate the potential for disaster if they struck a bird with their drone (and almost all birds will actively avoid being struck by a drone - even during the "mobbing" behavior that you cite above). I routinely fly drones in and among birds (for work-related reasons) and I have never had a single instance of a collision or near collision after dozens of flight hours with birds. I don't activate "avoidance behavior" - in fact quite the opposite - and I simply don't have any problems. Personally, I think that an abrupt, unpredictable increase in altitude would be more likely to catch a bird off-guard and potentially initiate a collision, than remaining in place or flying predictably.
People also think that their Mavic will fall out of the sky if they hit something but these are tough little drones. If you haven't watched the video of Mavic "toughness" tests, check out the one below. If a full bottle of water striking a Mavic a few meters off the ground isn't enough to cause a crash, hitting a small bird at much higher altitudes will probably not cause a crash either. Not saying that it can't happen, but most worries about bird "attacks" echoed on this forum (and others) and conclusions from analyzed flight logs that a Mavic fell out of the sky because it hit a bird mid-flight are probably overblown.
The one take-away from all of this is that a rapid climb seems to be the appropriate response to a bird/dragonfly/ufo attack. That should be our trained response with future incidents.
I know that this is the common conclusion drawn by most drone pilots on the Internet (based on their extremely limited understanding of bird behavior and flight) but as one that has spent many hours in the air around birds in flight (both with drones and manned gliders), I disagree with this conclusion. Yes, if a bird was actively "attacking" your drone (likely only with much larger raptors - though I fly routinely with them as well with no issue), this may be decent advice, but with almost all instances of birds and drones, the advice to simply "act normally" and ignore the birds is probably better suited for the situation.
I think the other takeaway is that no matter what humans think they saw, it is filtered through their experiences and biases and we are far better off reviewing the actual data (or video in this case) than believing eyewitness accounts. It's the same reason we should take all of the "drone" sightings by manned aircraft pilots and other such instances with a large grain of salt, because, as we have been decrying on this forum throughout a multitude of threads (check out the
peeping drone thread or the
airport shutdown thread as two very recent examples), everything sighted flying in the air is not automatically a drone and we shouldn't jump to those conclusions and instead we should evaluate the relevant information in context.