To illustrate the difference between "conspiracy" and "conspiracy theory":
About 20 years ago I read about a man who called police to report a burglary. He claimed that someone broke into his house, stole the hard drive from his computer, and replaced it with a less efficient one. The much simpler idea that he accidentally downloaded some malware which made his hard drive work less efficiently, never occurred to this guy. Instead of this simple explanation, he came up with a "burglary theory", inventing an impossibly considerate burglar who steals hard drives and leaves slightly cheaper ones behind.
Yes, burglaries happen. When your window is broken and your computer is missing, burglary is a reasonable theory. When your hard drive is not working quite they way you expect, burglary is NOT a reasonable theory.
Same with any conspiracy theory. Yes, conspiracies exist. Yes, law enforcement agencies sometimes find them, just like burglaries, and convictions result. No conviction ever resulted from an overly complicated theory that tried to explain an event which had a much simpler explanation.