There really is no shame in trading for a living. The problem is that some people will say "oh, I'm interested in that, can you teach me what you do?" and of course I'm not into revealing my methods to someone whom I just met.
Then there are the people who just don't understand what it is I'm doing and their questions can be tiring.
Some would argue that soldiers do much more bad in the world than good. What about advertising people? "Yeah, I'm designing another ad for Philip Morris that is targeted at 20 year olds and after than I'm doing one for Coca-Cola to sell kids addictive sugar water that will destroy their health". Yet these people are rarely ashamed of their profession.
I do respect most farmers, supermarket clerks, garbage collectors and janitors though as what they do is very much needed.