Politicians in democracies need a fallback career for when they lose office. Before capital controls were lifted in the 80's, economies were a lot more local: UK politicians would take positions in UK companies or institutions, French in french ones, etc. This did mean a certain amount of corruption, but it did mean politicians were highly interested in the success of national companies and institutions.

Now, most of our senior politicians go to the US after leaving office; so for consistency they adopt the belief that there is no downside to making the UK beholden to foreign companies, or becoming a nation where all the innovative professions end up building capital for foreign owners, instead of building strong UK companies. As a consequence of this, they almost compete to sell out the public. It's impossible for them to believe that what they were doing is a betrayal of their country, because that would go directly against their personal interest.