Question 1: To your knowledge has a Bitcoin cloud mining contract (or service that switches between contracts) ever been more profitable than just buying Bitcoin over a 24 month time frame in the last 4 years?
No there wasn't any. None last to this day at least. Maybe there was a CM service which was paying without problems but that was true till it ain't.
Question 2: In your opinion what percentage of cloud mining contracts or service providers are scams/ponzi schemes?
%100 every single one of them. Every but every cloud mining service there is offers a reference program. Means get more customers to me, earn more = Ponzi. You'll soon realize you make your money only from your refs but not your actual mining contract = ponzi.
Cloud mining = ponzi.
If it were profitable, they wouldn't share it with random people.
You wouldn't.
I wouldn't.
They don't.