One problem with mRNA is that 75% of its name is what it's built out of, and only 25% what it does. It'd be like if we called HTTP packets "hBits", flash memory words "mBits", text files "tBits", and OS kernel instructions "kBits". I can see how someone would be worried that putting tBits on their computer could potentially modify their kBits! What if all those bits got all jangled up!?
If we called mRNA a "protein print job" like pjc50 came up with, and we called our chromosomal DNA our "kernel instructions", etc., I think it'd be more obvious how silly it is to worry that mRNA is going to somehow alter your chromosomal DNA. The point is that there are a lot of different functional things and data structures made out of bits, and a lot of different functional things and data structures made out of adenosine, guanine, cytosine, and thymine/uracil.
To be fair (not trying to imply mRNA vaccines modify your DNA), there are a lot of systems, especially past but also present (with vulnerabilities), where the right (wrong) print job could end up permanently modifying your system's kernel instructions.
If we called mRNA a "protein print job" like pjc50 came up with, and we called our chromosomal DNA our "kernel instructions", etc., I think it'd be more obvious how silly it is to worry that mRNA is going to somehow alter your chromosomal DNA. The point is that there are a lot of different functional things and data structures made out of bits, and a lot of different functional things and data structures made out of adenosine, guanine, cytosine, and thymine/uracil.