For Callum Mills, it is not a memorable holiday if there is no danger involved.The Scottish YouTuber has made a living out of taking the road not taken, and it’s led him to some of the most unconventional travel experiences, like having dinner with gang members in Brazil and meeting Pablo Escobar's brother Roberto Escobar while visiting Medellín, Colombia.It all started when Callum, better known as Callum Abroad on YouTube and social media, was …