|Buying a politician is almost always an illusion you're encouraged to believe in because it drives donations.|
I worked with a home builder suffering from the delusion that they had bought the Republican Mayor of San Diego, Pete Wilson, before he became Governor of California.
Although Pete Wilson provided them with repeated assurances that he was bought in return for their major donations and assistance and he supported their pro-growth project plans, when the important decisions were made he wasn't at all pro-growth as he and his campaign posters described himself.
Undoubtedly your conspiracy mindset will insist he "obviously" received much larger offsetting donations from some anti-building donor, but the reality is they wouldn't give him a dime or the time of day.
This was entirely predictable, as Pete Wilson was slavishly following what his voters wanted rather than the desires of someone who had merely provided him with a lot of money and other support.
In return for money politicians are willing to be seen with you, and you get "access" to them. Having access is significant if they happen to agree with you and meaningless if they don't.
Only a very small handful of people are so corrupt you can actually buy them - and the FBI eventually arrests them.
What takes far more work than you're interested in is supporting and encouraging a politician who naturally supports your interests. In that instance you're not buying a politician, you're more or less helping a friend and part-time employee reach influential places.
Politicians, like all people, often believe things which are simply not true and events and laws often don't turn out they way they would have liked. They aren't trying to deliberately cheat and disappoint you. You given them far too much power in your mind.
As an example, Donald Trump said "Trade Wars are good and easy to win" because he's a moron without trade experience, not because he's part of a global conspiracy to destroy the US economy and betray your hopes and dreams or because major "anti-trade donors and anti-American interests" bought him. He's just a witless narcissist - no conspiracy needed to make him that way. With Donald access buys a lot because he always tends to agree completely with the person he spoke with most recently, so you need to buy frequent and continuous access