Because SF is dense and not particularly segregated (as far as US cities go) so wealthy white people are more likely to witness first hand or be victimized than in in many other places.
The easy assumption is that in cities like Miami, LA, Chicago, St. Louis, and (previously) NYC the violence was confined to particular pockets of the city e.g. those rife with gang violence. It was easy for ordinary people to avoid by staying out of those areas.
In cities like SF and Seattle there is widespread and visible chaos and disorder, even in the large shopping districts and tourist areas. This is perpetuated by their residents' indifference and acceptance of utter lawlessness as normal.
You could likely leave your car parked on the street during a night out in the aforementioned "murderous" cities and not worry.
In SF and Seattle there is a very good chance you will have your windows broken.
In 2022, Miami recorded 47 murders, and SF recorded 55 murders.
Yet SF has twice the population of Miami.
So why is every murder in SF hyped up as if the city is hopelessly broken, while you never hear about murders in Miami?
Even though Miami's murder rate is much higher?