I do not believe aliens exist, lol. "Aliens" are any living that exists on another planet, even a virus can be considered an alien. I believe these kinds of "aliens" exist, but not some advanced extraterrestrial livings that are going to destroy our civilization. Bitcoin was the creation of somebody who wanted to escape the control.
Aliens do exist because the president of the United States admitted it. Aliens probably did make bitcoin. Because if aliens could cast 3,000,000 to 5,000,000 illegal votes in the United States of America and not get caught, they could make bitcoin and not get caught.
There are two kinds of "aliens"..... The government is calling "Aliens" those illegal immigrants, and there are also other aliens which are the extraterrestrial livings that are supposedly smarted than us and can "destroy our world". I do not believe these kinds of aliens exist. The ones you're talking about are the illegal immigrants, but the OP wasn't referring to them.