I believe anyone who receives such large donations/speaking&consulting fees/etc will be influenced in some way. Even a person who staunchly believes he/she is immune to such things will likely be affected, and even if they aren't, they should avoid such scenarios to avoid the perception that they have been bought/influenced. We've seen this over and over again.
I'm an objective scientist, so it doesn't matter if I know which group is the control and which is experimental. Oh wait, now we know it does -- even those with good intentions may unknowingly bias the results. I'm an ethical journalist, so it doesn't matter if I accept a flight, hotel room, and fancy dinner from the CEO I'm going to interview. Well, yeah, it does -- both for your objectivity and for the perception it gives to others. I'm a doctor who went through 4 years of medical school, 4 years of residency, and then completely 2 fellowships, so while you might be able to influence others by inviting them on an all-expenses paid cruise and regularly sending your sales reps to their offices to give up-to-date information the latest research on your drug,
you won't affect me! Bring on the freebies!
Except it does have an affect on them. And so on.
e: perhaps examples from the world ofp olitics would've been better lol