Yes, Trump exists in the Marvel Universe, and Luke Cage made him his bitch.
And that brings us to the source of all of Wakanda's power and prestige: vibranium, a ludicrously strong metal that only exists within their borders. The Wakandans have used this one-of-a-kind substance to fuel their technological wonders, advanced weaponry, and sweet jungle-cat-themed battle-suits for centuries. Have they ever shared this revolutionary material with the world? Yes, of course: In the 1940s, while the Nazis murdered millions, Wakanda let the Allies have enough vibranium to make one oversized Frisbee. The creator of Captain America's shield, Howard "Iron Dad" Stark, even says: "What you're holding there, that's all we've got."
"We had a little more, but the Brits misplaced their kettle."
And that's it. That's the only time they've ever shared any vibranium. (We're ignoring any developments in Agents Of S.H.I.E.L.D., because so does Marvel Studios.) Keep in mind, Captain America didn't exist yet when they sent the Allies that vibranium, so it wasn't like the King of Wakanda said "I'll give you enough of our precious metal to make a boss shield for your superman." He just sent along a teacup-sized portion and went back to completely ignoring the world. Imagine how easy World War II would have been if the Allies had indestructible tanks -- they could have cut through the Nazis' artillery like butter. And what's more, hoarding this technology, which could theoretically create vehicles that were impervious to damage, kind of places the blame for every car, train, and plane crash fatality squarely on Wakanda's shoulders.