Language changes. Hackers generally aren't "people who use things in unintended ways" anymore either, but evil criminals on computers.

Well, yeah, it does, but that's an odd example I can't say I agree with.

https://www.urbandictionary.com/define.php?term=Lifehack

That's because of the subculture here. This is "hacker news" after all ;-)

https://www.merriam-webster.com/dictionary/hacker has the "illegal entry to computers" angle in both #1 (besides "somebody who cuts down vegetation") and #4. Day-to-day use of hacker, e.g. in the news, also concentrates on that (like on https://edition.cnn.com/search?q=hacker).

There are subcultures that keep the original meaning of meritocracy alive, but like with "hacker" that train has left the station a long time ago.

No, come on, I didn't hear about "lifehacks" here, I heard about it on other non-computer related sites where people were making fun of how stupid they were. So I think that means the whole concept was invented to appeal to people even dumber than the average person, which is evidence completely un-HN type people have some sense of hacking as being positive.

It's not like the positive sense is unrelated to the negative sense either. A clever shortcut/trick/program could be illegal or unethical or not depending on context.