He has experience living in other global cities as a reference to London and you don't.
I have lived in London, Newcastle, Sydney, Gothenburg, Stockholm, Warsaw, and Gdansk.
I have travelled the world most of my life, and I now perpetually travel, more or less living out of a suitcase. I have long-stayed in six different countries this year alone.
Refrain from sharing your opinions online unless you actually know what you're talking about. Clearly, you don't.
If your point was that San Francisco has more homeless, or that Chicago is more violent, well, I never disputed that did I?