Eh? By that argument we might as well all stay in and never go anywhere where people congregate together!
I mean that's what we do as a species or society or culture. We go to things together. We celebrate - be it theatre, concerts, festivals, demonstrations, transport, sports event, big public celebrations - eg royal processions or fireworks. Any big event requires policing and the money has to be found otherwise we would be in a situation where large events were banned.
Yes of course any large grouping of people is a potential terrorist threat, but horrific though it is, we should not be permanently curtailing our freedom in the face of this threat. I mean planes/cars/trains crash but we carry on using them because statistically the likelihood of our dying in one is small. It is still very scary but as Taz says the terrorist threat plays on fear and aims to destroy our way of life through these dreadful and insidious random acts.
Hurdity x