If you accept the validity of your first sentence, can you not therefore accept that the remainder is tripe.?
The UK will hit international legal difficulties , not just EU ones, if they attempt to bypass the Anglo Irish agreement( the so called Good Friday Agreement). That agreement was predicated on the assumption that both the UK and Ireland were members of the EU. There are a number of clauses in it and a range of rights ,committee, and councils . It is not open to unilateral repudiation. .
In my earlier posting I suggested that the money is not the overriding consideration that you think it is. When there is a need , money can always be found or diverted.
You use the word panicking describing the behaviour of EU officials, I would substitute being highly flustrated as the emotional state. Here we are nearly a year into the process and there are no suggestions that the UK has engaged in the process. If you have ever had the difficulty of dealing with a drunk or mentally ill person, one find it a very trying process. The EU is presumably attempting to negotiate with a schizophrenic UK team. The professional civil servants know, as do you also that remaining is the best option, their political masters are flipping and flopping , because neither faction has a clear majority and they don't actually know what they want.they have no mandate other than somehow to create an acceptable Brexit.