Used scooter from the dealer turns out to be an accident vehicle

Hello. Something incredible happened to me. I bought a used scooter almost a year ago at a car workshop with scooter sales for 750€. The scooter had a good 1500km down and looked visually new. According to the dealer he was driven little and is in top condition. I immediately noticed that the original mirrors (as seen on the manufacturer’s side) are not mounted. So, 2 days ago I met a friend of my buddy who happened to be my scooter in the garage saw. This friend lives about 10km away from me. He could immediately tell me the model and brand (Luxxon YX9) from 15m distance. He also asked me if I bought the scooter used and even had a guess with whom. This was true even. He told me that he was involved in an accident about 17 months ago, in which this scooter plays a role. My scooter belonged to his buddy at that time. The two are with their scooters side by side against each other dangers, whereby on my scooter the fork was totally bent and the mirrors were broken. Besides, the scooter should have been totally warped. Furthermore, further damage, which I do not know. Hadn’t the dealer had to tell me this accident? dear greetings