I think as long as the reseller one is exactly want you want & authenticated then there shouldn't be any regrets if you take it right now over the possibility of maybe getting this bag in Paris.
You said it very eloquently yourself, this is going to be
have a bag like this in my arms VS
hope to get a brand new one
(bold added by me obviously but I think you know it too
)
People will give different suggestions due to different weights they put on this "hope". This is probably different for everyone depending on one's risk tolerance / optimism etc. For me personally, if I am looking for a specific bag, the expectation of getting exactly that in Paris too low for me to disregard a good reseller option (expected value = probability * value, even if value is very very high, if the probability is 0.0001% the expected outcome is not that high).
You can't judge whether a decision is the correct one or not based on future information that you do not know at the time of making the decision. That is to say, whether you get a bag in Paris or not in the end does not change how sound your current decision to get or pass the reseller bag is, because that is not a piece of known information for you right now. Rather, you can only try to make a decision with "there is a chance that I will get a bag and that chance is low". The question is then, how much do you value this chance? That is purely up to you & good luck either way!
The only other thing I'd add is, if you get this one, would you still be trying to get one in Paris? If you can potentially afford two, obviously get this and then try for another in Paris.
Edit: oh and if you decide to try you luck, double check the return policy on the reseller, if there is some return policy with a timeframe that works for you, you can at least order the pre-loved one near the edge of the return policy (and return it if you get a bag in Paris).