Of course, the percentage of tenured winners varies a lot by fields. It's very low in the humanities, somewhat better in CS and math, etc.
Once you get tenure, if you ever do, you will indeed have a lot of freedom, but you will also have a lot of work to do. Sure you can pass grading and other jobs off to grad students and postdocs (which you were for the last decade...) but in many fields, the need to fundraise never ends. It's sort of like funding a new startup every year with a different set of grad students.
Most people don't want to sit alone in a closet and think deep thoughts (well, ok, mathematicians do...). But if you want to do something in the real world, you'll need funding, and that means writing a LOT of grant proposals.