Wegener was technically a meteorologist but his PhD was in Astronomy and he had lots of training in physics. He (among others) noticed that the shapes of landmasses seemed to complement each other. He had a great deal of observational evidence. and he really wasn't this lone figure crusading for drift- that's partly because when we write narratives of science, people like to hear about lone rangers who overturn paradigms, when really, most scientific paradigms are overturned by a large number of people collecting evidence that supports the new theory.

We can write whole books about the unnecessarily hostile response of establishment scientists to novel theories. I've witnessed it myself and sometimes it takes decades and deaths of older scientists to overturn a paradigm. That's not particularly fair, but it's not like scientists are magically ultra-rational, they're emotional human beings like everybody else.

There's a few areas where I don't think outsiders can realistically produce change: thermodynamics (see all the attempts at perpetual motion machines), the shape of the earth (see the flat earth "theorists"), and complex medical topics (see all the current noise about vaccines, cancer, neuro disorders). To contribute to these areas, you need to go see what other people painfully learned over centuries. And most of that is just not written down, it's transmitted orally within advanced educational systems (which is not great).