You should ask yourself who and why these politicians seemed to make sure it's a disaster.
Perhaps in the hope that enough will swing the other way and fall in to line?
Just look at what we have had.
From the Tories under May.
No Single Market, No Customs Union, No Delay, No Deal is better than a bad deal
and that had drifted to a current
Elements of Single Market, A backstop which replicates the Customs Union with no get out clause, A Delay, No Deal being ruled out.
From Labour under Corbyn.
No Single Market, No Customs Union (both in manifesto, honouring the result of the referendum
and that has drifted since the General Election to
a 2nd referendum where they will campaign for Remain.
This has been coming. It was inevitable and it will lead to a huge stand-off and possible a seismic shakeup in UK politics.