What the members of the party want does not always align with what elected MPs think is best, nor what the public as a whole believes.
This time around, the requirements to be eligible to proceed in the contest were tightened - candidates needed 100 MPs supporting them. This was designed to speed up the process considerably.
At the deadline, Rishi was the only candidate that met the requirements, so he won by default, and there was no need to have a ballot of the members.
Party members "overwhelmingly" voted Truss. Rishi Sunak isn't liked by the people that matter most - the party members, and seemingly, the electorate.
Basically the Tory party is back where it was under John Major in the 90s. In-fighting and completely ignoring what the electorate think. It's odds on that Labour will get into power in 2024, not because they have the plan and the policies, but simply they're not the Tories.
It really is a case of 'those that don't learn from history are doomed to repeat it'. And here the Tories are. Arguably the last time Labour got elected on their own merit was many, many decades ago.
Frankly it's tedious to hear adversarial politics in Britain. But that's all we're going to get from the Labour Party for the next 2 years. They could be laying out policies, preparing for government, being an adult political party, and ignoring the Tories, because frankly, no one cares about the Tories at the moment. But Labour won't do that.
UK politics is a sewer.
Cancelling the increase in National Insurance: Well, Hunt has said this will remain cancelled.
Cancelling the increase in corporation tax: Welcomed by economists and businesses. Increase is predicted to make recession worse.
Reducing the additional rate: Definitely not the right time, but note that this rate has only existed for 10 years.
So it is not that the policies are "widely regarded as utterly batshit". Individually they are not. But they were announced all at once without any hints of funding and that's what spooked the markets (more debts and fuel for inflation when the situation on both fronts is already bad).
Last time, Sunak got the most votes among MPs by some margin, with Truss coming second; but Truss won when the vote was put to the party members (possibly because they were very pro-Boris Johnson, and regarded Sunak as disloyal, seeing as it was his resignation that effectively forced Johnson's).
This time, Sunak was the only candidate to get enough nominations to run at all, so he won by default (though the number of nominations he got showed he was again the clear favourite among the party's MPs).