"Is there a royal family in modern America?"

There are several families that have members the Queen of England has elevated to the English nobility.

"Why is Kennedy's assassination the subject of a conspiracy theory?"

Because JFK was assassinated, and it was done by conspirators. I have not mentioned it, but understanding the crimes politicians and their ilk commit, what you refer to as conspiracy theory, is not merely a mechanism to create a shared culture in America.

It is necessary to save our lives from murderous criminals that seek power at any cost, including the lives and treasure of civilians, like us. Genocide and crimes against humanity aren't fantasies. Massive drug smuggling operations, organ trafficking, and child sex slavery are ongoing today, along with wars and other vile crimes, and threaten the peace, freedom, and prosperity of all people, including Americans.

I have been physically attacked and my family threatened for knowing of and opposing crimes undertaken by goverment. That is not a theory.

That's a beating, and an existential threat.