How does being in academia help researchers
Beyond the obvious benefits of financial stability, one must also consider the possibility that not all researchers are solitary creatures. This is especially true in the non-mathematics parts of STEM fields, which frequently require collaboration to achieve meaningful results.

Moreover, there is the additional issue of the amount of work that one person can get done relative to the number of ideas and projects that they want to explore. For instance, right now, there are about a half-dozen different project ideas that I'd like to work on, and I could probably come up with a dozen more if I had the time and space to do so. But I only have a finite number of hours that I can work, which means that I have a few options:


find people who are willing to work on those ideas by getting a grant and hiring graduate students or postdocs,
do it myself, or
leave the work undone.


The last option is unappealing, and the second is basically impossible without burning myself out after a few months. So that leaves the first option, which is difficult to do if you're not affiliated with some sort of research institution.