Imagine your fingerprint data is leaked to hundreds of hackers.
Yeah, I'll risk it...
Individuals who had their fingerprints stolen in that hack can now never use fingerprint readers with any reasonable confidence, since now all a hacker has to do is search that person's name and pull their fingerprint from one of aforementioned databases.
> fake your fingerprints with a cast
Fingerprint scanners like those on phones have been shown to be able to be fooled by using $10 worth of office supplies and some play-dough. It's not like we're talking mastermind levels of intelligence to do this stuff.
Of course, all of this completely ignores the fact that your phone likely already has several copies of your fingerprint already on it since you touched it, so it's not like someone hacking your fingerprints is even necessary. That's an entirely different reason of why fingerprint security is abysmal, though.
2) google "touchid hack" there's videos on YouTube.
3) not super likely as usually you'll only find rough partials, but as previous poster mentioned, there has been government hacks that have leaked biometric data.
(That said I never had a phone lost or stolen. People who tend to have them so might feel differently).
Because you expect repeated attacks from the person who stole your fingerprints? Who are you, James Bond?