Historically senators and representatives side with companies who've only given them thousands or tens of thousands of dollars in contributions. It's very cheap to buy a vote.
Though often there's also the understanding that a career spent supporting them will be rewarded with a cushy, high-paying lobbying job once they leave politics. Or paid speaking gigs if you're the President.
It's not incompetent to give someone a penny and have them give you back $100. That's a great investment. So I would have to say their corruption is very confident if they can give a million dollar bribe and get back a billion dollars of revenue.