The EU is about to allow the UK to break away and cripple European trade.
The UK is the largest Export market. Without a very good trade deal, there will be millions of Europeans losing jobs. Ther car industry alone supplies the UK with parts from Poland, Germany, Italy, etc. French cheese, wine, farmers will lose a huge market. I could go on but won't.
This chart shows how much the EU relies on the UK for jobs.
There are non-EU countries who can supply those goods to the UK the moment we leave. What do these countries supply that can't be bought elsewhere?