In general I suspect these huge classes have not much to offer for an advanced dancer.
When they are held in a city, they are not huge. Sometimes the capacity might be capped to 30 or 40 dancers. I have seen a lot of advance dancers going to such workshops. To them it is like a challenge of doing something new.
I spend 3000+ Euros in private lessons during those two years of Covid times (while I saved money from not doing much else due to Covid).
30 privates? 15 privates a year? Absolute total amount appears very large but broken down by number of privates it is at par.
Now that you have invested (not spent) this much money, you should go to all the big congresses to recoup the ROI by actually spending more euros