Facebook and Google are still around. There is absolutely zero risk of any significant GDPR fine as long as the biggest offenders are allowed to run freely.
I think it would be unsafe to assume that there is zero risk of significant GDPR fines on the basis that the regulatory bodies have not picked a battle with google and Facebook.
Smaller organisations that seem to be doing less to respect GDPR are probably an easier starting point for regulators to begin enforcing the law.
Also: How are Google and Facebook offenders of GDPR?