Sure, the probability is lower than getting struck by lightning. I certainly don't play in the rain and I won't be using cloud services where I'm exposed to this kind of nonsense with the FBI.
I don't think anyone can actually know that, because I don't think statistics are kept on how often these sort of dragnet programs result in civil liberty violations and secret grand juries. That should be the more immediate concern, because after that point you are depending on the goodwill of prosecutors... which is a super bad idea.
Just reading those words is rage-inducing, but I'm grateful to have learnt this example of government lying. I feel like it should become an expression that societies teach to their children to warn them about abuses of power. Other mottoes synonymous with government deception and corruption come to mind, but at the risk of being too controversial I will share only their initials and dates: "SAARH" (2013), "MA" (2003), "IANAC" (1973), "NHDAEMZE" (1961), "AMF" (1940).
Nice big clean sample? It probably actually matches. Small sample? Mixed with other people's DNA? Especially in a place they tend to visit (or live in?)?
"Following the 2004 Madrid train bombings, fingerprints on a bag containing detonating devices were found by Spanish authorities. The Spanish National Police shared the fingerprints with the FBI through Interpol. Twenty possible matches for one of the fingerprints were found in the FBI database and one of the possible matches was Brandon Mayfield. His prints were in the FBI database as they were taken as part of standard procedure when he joined the military."
"The FBI described the fingerprint match as '100% verified'."
https://en.wikipedia.org/wiki/Brandon_Mayfield