oh god please make this happen
This would be amazing indeed!
Unfortunately thats not possible, first you would need extremely low hanging clouds(preferably flat ), then the image would be blurry and most importantly only recognizable from 1 position.
Projecting it on some skyscrapers would be much more effective, preferably from a construction(like a crane) on the building itself.
But then again you have the problem of permits, which Germans are a huge fan off.
You can always do it old school and hack a building to play around with the lights:
You have thrown megabashes before yes? Please tell me this isn't your first rodeo...
First you do the fireworks, start small, build to a crescendo, timed with the suitable music. Build... build.... then finale! Everyone is overwhelmed by the display, It ends with a big bone-rattling finish, and silence... Into that sense of overwhelming awe and onto the layer of high smoke from all of this explosions, you project the B in silence, in all its glory, standing alone for all to see...
The symbolism will rest in the subconscious off all who bear witness, that after the struggle and the currency wars, after the tumult and the strife, there will be peace...and bitcoin.