You could literally wear what you wear now.How should one dress in Colombia to not get robbed? I dont want to trick but I read the nightlife and airbnbs or hotels are cheap with American dollars.
If you really want to look like a Colombian I guess you could wear a Polo top with some dressey jeans with some loafers that's the standard Latin American casual wear.
Of you could wear either a nice Hawaiian shirt and some slacks and a panama hat.
But young Latin brehs basically wear the T-shyt and Ball cap that's worn universally.
If you don't want to get robbed avoid eating at streetside restaurants especially outside other than that don't use Tinder and you're chances of being robbed will be slight.