Unauthenticated http is a vector for opportunistic malware. They don’t target specific websites, just inject evil.js wherever.

You ISP sniffing and MiTMing traffic on the wire is the least likely vector of malware injection.

ISP's are usually serious businesses with reputations and don't hack their own customers.

That “usually” is doing a ton of work. I remember Vodafone injecting scripts into webpages many years ago. While trying to find a source, I bumped into other shenanigans.

https://www.simpleanalytics.com/blog/vodafone-deutsche-telek...

Out of all the bad actors on the Internet, your ISP is the least bad.

That’s not a valid defence, it’s moving the goalposts and whataboutism. ISPs shouldn’t be bad actors at all and they have the ability to do the most harm.

Maybe if they live in a high income country with relatively strong consumer protections and are using their home ISP. But quite a lot of the internet is very much not that.

In some places and on some networks, MiTMing http traffic for undesirable use-cases is routine.

At least so that login / register data don't go to the middle man.

You don't. But you will be penalized by Big Co for not supporting https.

(It's effectively a "doing business on the Internet" tax. Thankfully not that expensive for small hobby projects now.)

It's literally $0 with LetsEncrypt.