Whilst we're sharing.
I was going to lunch with 3 other fellows in my truck.
A man sped around us on his bike (temp tags proudly displayed), and locked up the back tire trying to stop (speed too fast for skill and condition).
He managed to get the bike stopped, but failed to put a foot down, so over it went on the left side of the bike.
We stopped, said nothing, all three got out, and helped him right is bike.
He thanked us quietly, and explained he had just picked it up, and was riding it home.
My guess -- no experience, and no training. Fortunately the only damage was his pride, and a lot of damage to the bike.