As long as extreme wealth inequality exists, politicians will keep being bought and sold by the minority for their own interest at the expense of the majority.
Even if the political class don't rationally understand everything they do, they are very good at dressing their apelike dominance-pleasure in saleable words instead of naked aggression, because modern politicians are essentially just trained PR mouthpieces. What they are doing feels right, and that's enough reason to continue because they are addicted to power, one of the most addictive things we can experience. It's perverse and we're all trapped in it.
I present Liz Truss as a counterexample.
The current government have largely given up on that goal - they're so disastrously far behind in the polls that they're facing a historic defeat and staying in power is a near-impossibility. They've fallen back on a damage-limitation strategy, using culture war wedge issues to try and secure their base and set a lower bound on how badly they'll lose. They're positioning themselves well to the right of the median voter, because they simply don't have the credibility to fight over the middle ground.
https://www.politico.eu/europe-poll-of-polls/united-kingdom/
https://edition.cnn.com/2023/09/20/uk/uk-sunak-climate-targe...
https://www.nytimes.com/2023/09/04/world/europe/uk-rishi-sun...
Not that our other options at the moment are a significant improvement.