Nothing of value will really be lost, replacements would spring up super quickly and I'd like to think that we would have learned enough about the downsides of the current social-network systems for the next generation to avoid the pitfalls and hopefully make something much better.
That’s the point. Google recently came of comparatively well with a 4 billion EUR fine, but 2 more fines of the same height for Google are expected.
The only way to force a company to follow a law is to make infringing the law more expensive than any profit you could ever dream of making from it.
There are lots of things that constitute an infraction: the GDPR aims to broadly protect EU citizen rights. Some infractions can be per individual harmed.
And European courts consider intent carefully. Mere aggregation of personal data isn’t necessarily a violation, but using it commercially almost certainly is.