How did America allow virtually all our politicians to be corrupted by outside corporate money?

This is a negative side effect of capitalism. We love capitalism but apparently we are completely unable to control it, to minimize the damage it does. This is why we have periodic market crashes and recessions, why we can't stop pollution or the destruction of our climate, and why politicians can win by setting us against each other. And why the great majority of us have grown slowly poorer and poorer for 4 decades now.

I'm becoming convinced that capitalism will eventually kill us all.

By voting for crooks, rather than for those who are honest.

Its been like that for 100s of years

It's been that way all along.

Because one of the most decisive, if not the most decisive, factor in being elected to office is the ability to outspend ones opponent. Wealthy individuals, lobbying groups, and PACs are able to pour money to candidates, on the condition that person will vote their way once elected. Court decisions in recent years have exacerbated this problem, and incumbent politicians are reluctant to change the system.

I agree that the Deep State's opposition to Trump is based on their vaild fear he will reduce their self-given power since Trump is too personally wealthy to be bribe-able.

Politicians were corrupt since civilization began

Perhaps if we did not see it as a job of the Government to regulate the Crap out of companies, they would not be resorting to such trickery to get out from under the boot on their necks?

Because america is a landmass and landmasses can't do anything -.-

This didn't happen. The liberals were only concerned with campaign finance only after they were voted out of office at every level of Government.