The highest GDPR fine was 1.2 billion. As far as I know nothing is stopping the EU from imposing higher and higher fines with continued breach of guidelines there, and I would expect these fair market regulations to work similarly.

Also for reference, that fine was against meta, who had 34 billion in revenue in 2023. So that fine cost them around 3% of their global revenue, which I'm sure is tolerable, but definitely approaching the point of hurting.