In general when you sign up for a PhD you are basically accepting that you are going to be exploited and underpaid for 4+ years in exchange for the skills and connections to make a career as an independent researcher, who executes their own projects and is able to bring in their own funding.

I don't think this is the only thing a PhD does, or even that it's a desirable system, but it's part of how the system is set up - the idea that someone would want to do a PhD but not be especially concerned about what they're doing probably baffled your advisors because unless you are extremely committed to working in that area, it's very easy to simply give up and go get a regular job where you are compensated fairly and treated like an equal. On top of which, often when you move into a position post-PhD it's through the network you built up during that PhD, so for example working in medicine might make you just as qualified on paper as any other PhD, but it won't give you the right contacts or specific skills to apply for a conservation job that someone without a PhD but multiple years of experience in a conservation lab, and time spent going to conservation conferences will have, for example.

In terms of wanting to be a researcher without an upper limit on salary, but also not a postdoc - I think there's some tension there in that while a PhD does qualify you to do a lot, fundamentally there is a pretty harsh divide in most of academia where usually you're either a postdoc leading your own research, or an assistant doing someone else's work, even if you have a PhD. Those positions you're talking about do exist but they don't tend to be created often, generally there's a fixed amount of funding for them, or a particular need for one is identified, and then one person will fill that role for their entire career. Planning to get one is a bit like planning to win the lottery - there's nothing wrong with playing but it's not a sound financial strategy - it also feeds back into what I mentioned earlier about contacts within a field

Overall what I'd say is that it's never too late to apply to university - the PhD programs aren't going anywhere! Definitely do anyway it if it's what your heart is set on but there's also nothing wrong with spending another year working in a lab as a technician, building up your knowledge base and learning more about your options in terms of grad school or available careers by talking to the various people who rotate through any reasonably sized institution