"Very invasive" has a meaning that could very easily be connected to discomfort and feeling like they're expected to be vulnerable in an environment that doesn't feel safe to them. This is also a teenager who may not even recognize that that's the issue they're having, or may not want to share that readily with a bunch of strangers on the internet. Generally people who have therapy forced on them rather than presented as an option aren't too open to it, especially if it's forced on them by the very people they're having issues with, which could easily be the case here. We don't know.

What I'm saying is that it's not helpful for you to jump to negative conclusions about this person without knowing any of the details. People don't refuse needed help for no reason, so the fact that this person needs help and still isn't open to the help that's being offered to them means there's a barrier there. We don't know what the barrier is, but just assuming it's a character flaw isn't helpful. It places blame without offering any solutions (other than arguably "stop whining", which is really just telling this person to shut down even more rather than open up). My suggestion to you is to hold back on the judgements in the future and assume the best of who you're interacting with unless they give you legitimate reason not to. Advice given from that perspective is so much more likely to be helpful than advice that comes from the assumption that there's just something wrong with someone and they need to fix their attitude.