But why wait until the EU is being beastly Prime Minister?

Theresa May has told us all that if the Europeans are beastly to us over the Brexit negotiations then she'll show 'em. It will be more than just wind signifying nothing too, she'll create a lot tax and low regulation Britain just to show those continentals:

In comments that were hailed by Eurosceptics, the Prime Minister told EU leaders that any attempt to “punish” Britain would be “an act of calamitous self-harm for the countries of Europe” that her Government will not accept.

She said she would rather do “no deal” than one which is a “bad deal for Britain” and said that any attempt by the EU to harm the UK would force her to change the country’s “economic model” by lowering tax and cutting regulation to compete with Brussels.

The question that pops into mind here is, well, why do we need to wait for Brussels to be beastly? 

Of course, around here, we generally support a lot tax and low regulation model anyway. But the PM is stating there that such  a model would be good for the UK. For it would allow us to compete with Johnny Foreigner - presumably making us richer as we did so. And given that that is the case, both from her logic and also from the basic fundamentals of the subject, why are we waiting upon J. Foreigner? 

Why don't we just get on with having a low tax and low regulation economy and country? That is what Brexit gives us the freedom to do after all....