The base construction is not unsafe, the placement and closing the construction by huge sails made it vulnerable.
The main thing is that the location of such a construction plays a huge role in possible safety issues.
Build it inside a football stadium and it can stand with a lot of wind. Put the same on an open plain, maybe enhanced by a natural funnel and it goes down.
the simple fact that it was videotaped shows that it was probably already rattling, which leaves blame on the orginaizers for not securing the area in time.