Should people be concerned about risk of terrorism at places like Mardi Gras?

Worried about home grown terrorists, not so much. Worried about the crime in New Orleans that has filtered into the parade routes and into the French Quarter over the last couple of years - absolutely. Especially in the crowds. Thugs shooting into crowds without regard for life should be a concern. As a former St. Tammany Parish Sheriff Deputy, I worked many, many parades, on the South and North Shores all the way to Picayune, Mississippi, and every water parade over 6 years. The closer to Fat Tuesday the larger the crowds along the parade route. Easily exceeding over a million people. Yeah, ever vigilant. As the party flows into the Quarter and the crowds are so thick that your best bet is to grab on the tail of one of the horse patrols to get from one fight to another, the scene is crazy. I enjoy watching people having fun, but after 6 years of working them, I seldom go to them as a spectator, and now only if family has come to town specifically for them.

It definitely is and there will be people who feel disenfranchised and have nothing to lose. It seems there are a lot of factors here including cities like Detroit destroyed by the death of the auto industry.

To a point, they have it right. The whole point of "terrorism" tactics is for a minority to affect a change in behavior in the majority by scaring them into acceding to their demands. We must be vigilant, but the best way to undermine the tactic is to remain committed to our way of life.