Then something came back to me: perhaps obvious, but (IMHO) enlightening in its stark simplicity. Years ago I came across a quotation - that inevitably I now can't find** - from a senior politician of the 19th(?) Century which ran roughly as follow: to be Prime Minister of Great Britain for even a single day! Did ever a Roman emperor of old wield even one tenth of the power?
That captures a particular world-view rather neatly, and it occurs to me that the problem resolves to this: there are enough shameless politicos for whom it is their one and only guiding light, so that they will risk any amount of collateral damage to achieve it. So what if it lasts only a month? That it ends in utter catastrophe? That their name will be dirt forever? They will have had their 'single day'; and that reviled name will at least forever be on the roll of Prime Ministers of Great Britain.
It's even better (or worse) than that. There is so much time before the putative 2022 GE, they might get hundreds of days! And in such a long time, Something May Turn Up! It's a no-brainer - what's not to like?!
The will to power (© F.Nietzsche 1883) is so powerful that for people like this, no further details are required. As Robert Redford's newly-elected President asks in the closing sequence of The Candidate:
"What do we do now?" Then the media throng arrives to drag them out, and he never receives an answer.ND
** a small prize for anyone who can turn it up
UPDATE: reader Carl Edman has turned up the quotation
- it was Melbourne, see comments below. Good man! - he can come again.