Your estimation is way off.
Event started 12 days ago.
Let's assume you take 15 minutes to make a POD room, start the quest, finish the boss and return to lobby.
I will not take HH into consideration but won't take DAR reduction either so that they kinda compensate each other.
I'm not even taking Kondrieu appearance either into consideration, which saves you ~1/10 run.
Assuming STA is 1/300 (3x easier than your theory), it means you need to farm 25 PODs a day during this whole event to get one in average.
25 PODs, with 4 PODs an hour that is 6h15 of farming.
I really don't think you ran 6h15 of only POD everyday since this event started.
Either way it's all about RNG. Some lucky people find an STA in their first run.
I myself have not found any STA for 3 years now so trust me I know the pain.
In 2015, someone ran 877 POD before getting their STA, all on shared dropstyle so no DAR reduction.
Some people complain before they even made a tenth of them.
We all know STA is not an easy drop, and that is not surprising for the best armor of this game,
which can give you immunity to any magic attack.
Don't forget odds get lower with players number: in a 4P room, 1/300 becomes 1/500.