…and plenty of other attacks in the past ten years.
Furthermore, Säpo (security police) estimates there are roughly two thousand salafists in Sweden willing to use violence to overthrow democracy and institute sharia law.
For context, given the Swedish population of 10 million, that’s roughly one per five thousand. Quick math makes it ten in my hometown and thirty in the city where I work/go to university - odds are that I’ve met at least one.
It has happened and there are plenty of people willing to perpetrate new attacks. I’m willing to bet a lot of money that it will happen again, maybe not at eurovision, but it will happen. So, yes, I worry and I take precautions (similarly to how I wouldn’t walk in certain parts of town at night).