Yep, in this article
the age factor is explained pretty clearly, plus as you said patient 1 (we don't know who patient 0 was) had the virus for weeks while he was running two marathons around various towns and went out to play amateur football. When he fell ill he went to the hospital/GP (thus infecting loads more elderly and frail people) but they didn't identify it as covid-19 and sent him home with medicament. Then he was brought back to the hospital when it turned life-threatening but they only diagnosed it as covid-19 when he was already in ICU. So his second trip to the hospital also infected other people. So not a very lucky situation for our first covid patient.
I don't know if age + our bad luck with patient 1 explains it all, but it certainly explains a bit of it.