In reality, nothing is that hard to do if one sets one's mind to do it. Like it's taught in basic philosophy that the human mind is a tabula rasa. It's a plain sheet until life begins to write on it. Maths and Further Maths were assumed to be among the toughest subjects in high school a few years ago. Even at that, there were students who found them very easy. Such is life. At present, there are stories of teenagers solving mathematical questions that adults who are science inclined aren't able to solve. To that point, I think it's not enough to to say something is hard when it hasn't been tested. There should be grounds for this. Even if it's difficult, there are going to be some who will find it amusing and interesting. Teaching or learning cryptocurrencies wouldn't be any difficult that learning nuclear physics or thermodynamics and others.
Still, I think to know the ins-and-outs of crypto, one really needs to get an understanding of signatures, hashes and hashing, and cryptography in general. How hash functions work and how its applied in the world of security is pretty crucial to crypto I'd say. Forcing learning about another subject - something that students aren't interested in much would just increase a lot of pressure on them and they'd just end up ignoring bitcoin - saying that its a redundant thing because we already have a method of transacting money.
Also, just in my opinion, many might disagree with me, but I feel like a great many among high school teachers don't know what bitcoin is/ dont know the workings of it. I doubt they're really the best people to introduce students to topics that are as technical as bitcoin, seeing as the biggest complain with schools is that they dont "teach us how to do taxes" - thats really the cliché, but you see where I'm going with this - schools arent the best at teaching topics that relate to real world finance.
College/university professors on the other hand are much more inclined towards recent developments (atleast in my personal experience till now), and specially in fields like CS where they are already aware about hashing, modular arithmetic, number theory - some stuff which is really the foundations of bitcoin, they'd be much better equipped to teach the future generation about bitcoin. Sadly, most college courses don't really have an elective that focuses on the blockchain or cryptocurrency as a whole, but I'm hoping that can be changed in the future.