The Congratulations Google User You've Been Selected threat is probably a potentially unwanted app. There is also a chance it could be related to Mac malware.
If so, such apps tend to slow your Mac down siginficantly and display advertisements. They could also use cookies and other trackers to obtain browsing information from the installed web browsers on your Mac.
The creators of such unwanted apps work with pay-per-click schemes to get your Mac to visit risky or different types of websites that may generate them funds. This is why they do not even care what types of websites show up on the ads. This makes their unwanted software indirectly risky for your MacOS.