Alternatively, how about the UK does what they want and you get nothing?
That's not how things work among mature politicians (excl. your childish President).
There needs to be some sort of agreement in which the UK pays a certain fee to leave the union, so that they can get fitting trade deals after they have exited. Otherwise, if they are too selfish the UK could get punished again later and nobody really wants that (on both sides).
"Sometimes, it pays to be a little wild" - Donald J. Trump, mid 1980's.
