Also, the stats for cars show that speed increases cause deaths to go up non-linearly, so your chances of dying in an accident are way more than double at 100 vs 50 km/h.

I would assume the same about motorcycles and ebikes, but presumably the threshold would be lower due to lack of protection (motorcycle helmet and armour not as safe as a metal shell with airbags).

So I wonder where that curve starts to rise up on bicycles and ebikes considering they wear just a bicycle helmet and no armoured clothing usually.

(I loved riding ebikes in China (Kunshan) with wide protected lanes that were totally separate from traffic outside of city center (where speeds were low and congestion high, negating they need)).