All It Takes Is One Encounter
Dr. Eugene Smith opened up a sustainable micro wormhole via a particle accelerator. He took snapshots though a portal to the edges of the galaxy and beyond.
Eugene discovered inhabited planets and intelligent species appearing to trade, war, and travel. Entire solar systems occupied with life.
Knowing full well the impossibility of physically transporting himself at the speed of light, not to mention so many lightyears away, Eugene developed a two-way holographic transmitter. He beamed a data stream of himself through the wormhole.
"Marvelous!" Eugene stood in front of a humanoid alien. "I don't know if you understand me, I come from Earth."
The creature transmitted thoughts using holographic signals, and Eugene somehow understood them.
"Of course, Earthling. We all travel through wormhole-holography. How else do you think I understand you?"
"You mean you've visited Earth as holograms?"
"Of course, flying saucers, little green men, grays, you name it. We appear and disappear all the time. Sometimes the transmission gets fuzzy through your atmosphere."
"So wait, you've never landed on Earth?"
"Yes, obviously, don't be naive. Do you think any of us truly interstellar travel?"
"But I see ships, trading posts, battles, and all sorts of interstellar travels."
"Holograms, human. We connect and communicate digitally amongst each other."
"But here on Earth, we also make physical connections."
"Human, that's just dangerous and foolish!" The alien laughed. "Any first contact might lead to utter devastation. Powers for good can always be weaponized. Fortunately, the universe prevents that, else, we'd destroy each other. All it takes is one encounter, and, well, you know the result."