In the case of Modric, there is a get-out clause: All teams playing in Europe next season must abide by the Financial Fair Play rules, which would explain up to a point why Chelsea's offers have been utterly derisory (as well as why Liverpool are suddenly chucking cash around so readily - they don't have to abide by the rules as they aren't in Europe.)
When a club is more concerned with not losing more than £40m next season - which would mean they were disqualified from European competition the following season, and would continue happening due to Chelsea's inability to grasp the concept of being self-sufficient - than they are with securing Modric's signature, pointing this out to him would remind him that we can compete in Europe under these regulations next season, and presumably into the future.