I get annoyed with people describing it as a 'protest against the travel ban'. That makes it easy to dismiss if you think he is right about the threat.
For me, it's far far more than that. It's the whole messages he is saying and the direction he is going, and the fact the UK is riding on his heels because of Brexit.
The travel ban is just one symptom of this journey he is taking the USA and the rest of the world on.
That's why I am protesting.