With the best will in the world, and without meaning to belittle the atrocity that happened last night or sound callous, let's look at the numbers:
The capacity of the Manchester Arena is 21000. By all accounts, last night's show was packed out.
22 people died. About 0.1% of the people there. When you account for those in hospital then roughly 0.3% of the people in attendance were hurt or killed.
In short, had you been in that arena last night you'd have had a >99.5% chance of coming out unscathed.
And how many people are in Manchester? The population is 2.55 million according to google. The 21000 people in the arena who were caught up in the worst terror attack on British soil since 7/7 represented approximately 0.8% of the people in the city at the time.
Again, I don't mean to make this sound trivial, or to try and dismiss the heartbreak of those currently going through this horror, but the point is your odds of being caught up in something like this are tiny.
I also live in London and sometimes I wonder if it will be my train that gets targeted, or the street my office is on (I work in the City), or whether I'll be out at a restaurant with friends and some nutter decides to strafe the building.
I am sure I could live a very safe life if I stayed at home and never went anywhere. But what kind of life would that be?