If your machine gets locked down by one of these scammers you can fix it yourself.
Download and burn a trinity rescue disc.
Follow this vid.
Unfortunately they don't lock you out of your machine. Instead they encrypt all of your data so that it looks like jibberish.
The weakest link in the chain is almost always the human sitting at the computer. Got the panicked call from a client Monday at lunchtime. "All of our documents have weird icons, someone admitted to opening an attachment to a spam email" The spam slipped through the filter, it looked like an invoice, and the finance person opened it.
150Gb of data borked. About 2 hours to restore from backup, 1/2 a day of work lost for some of their users, and 2 computers to nuke and reinstall. It could have been much worse.