The problem with demonstrations is that half of the time, people demonstrate against each other’s causes. Or just for causes with unclear sign or scope of impact.
The whole thing has huge overhead; it blocks the streets and disrupts everyone, and additional police have to be paid to secure the whole thing.
On the other hand, there is no doubt some demonstrations have been of great historical significance.
So make sure this is worth your time, compared to just sending 20 bucks to some random effective charity,