Nope! No need to use the article. "No matter what people say, black cats do not bring bad luck." It sounds strange most of the time to use "the" before people, unless you are speaking about the people as a political group. ("The people have spoken!" "Power to the people!") or if you're speaking about a very specific group of people that you will define in the same sentence: "No matter what the people who live upstairs think, it is rude to make a lot of noise after midnight."

You listen to not enough Reggae music: in that case you would have remembered a verse of "We A Rockers" by the Inner Circle: - no matter what the people say, I keep on jammin' every day .. do you love me -- yeah! -- do you love me...