A degree in anything is only going to get you so far. Its like the gateway to your future, as in it gets you through the door. Ambition and the willingness to do is going to determine how far through that door you go.
Yeah sure there are other important factors too. Also luck plays a huge role. It's just that a degree is a base for most people.
I'm going to disagree with your first paragraph. I think the people who truely do like sciences are the same people who like history and vice versa. See, the people who like these things and succeed in them like to understand and gain knowledge about everything. At least thats my experience. Some people just have a greater passion for one of many subjects those two titles encompass.
I know people who like history but hate science. And I don't mean science like watching discovery channel and science news - they hate maths, physics etc. They're happy about their history or whatever they're studying.
Actually I have quite a lot of friends who dislike science.
I also know people who are passionate about their own interest without respecting other fields.
In my opinion science requires an entirely different approach that not everyone will understand/like/handle. That's why you can be great at history and suck at maths and in some cases hate it because of it.
I think that subjects like History are easier for any average guy - and I mean easier to learn and enjoy because of how you make progress and how you learn. That's because you can take any piece of information and understand it with basic comprehension abilities.
With science you can't go and say "okay, I want to learn quantum mechanics today" without understanding maths and physics really great. And to understand them you have to study and practice piece by piece in a specific order which might be boring, demotivating and not rewarding at all since after months you still won't be able to understand more complex things. Science means taking challenges all the time.
In history you can just skip things that don't interest you while in science you have to understand everything, if you won't then it'll kick you in the balls twice as hard later. With history you can read fast and try to remember as much as you can, with science you don't read much but analyze everything, spend much more time trying to understand and practicing. And practicing a lot.
It's a different kind of approach that a lot of people don't like.