I spent the best part of a year building a bike for the Elephant Rally (a winter bike meet in Germany if you don’t know it). It was stolen on my shakedown run while I was having lunch. I never did see it again.

I had the battery stolen from my bike in Venice when I was doing the sights.
I had my gloves stolen from my seat while I was putting my helmet on! (a young kid took them and ran off - I ran after him and got them backwhile wondering what his mates were taking while I was away)
I had the top box and panniers broken into and loads of stuff taken when I was in Spain. That was overnight in a hotel where the bike was in secure parking with a all-night guard. The hotel denied all responsibility (of course) and the guard “saw nothing”. We had to leave early to make a ferry.

Having said that (and there were other thefts I won’t bore you with listing) I’ve lost far far more stuff than I’ve had stolen. I’ve lost a couple of tents and loads of sleeping bags, mats, cooking gear etc. Also bike jackets (at least three I can remember), trousers, electronics, even the occasional bike part. We once (a long time ago) lost all our money (back in the days when you had to take cash). That was a tricky one to fix.

Last year we were coming back up the M20 from Dover and were overtaken by a couple on a 1200GS. Just as they came past something fell from their bike. I recognised it as their sat-nav as it just missed us and slid past on the concrete. Unfortunately the truck following along didn’t miss it. Last time my sat nav mount snapped I caught it on the way down. They weren’t so lucky.