All the people around them are supporting them, how do you know they're really worth it? If a physicist spent 40 years producing useless stuff, would anyone notice? Does that matter? How many string theorists should we support as a society, anyway? And why say, researchers? Why not artists, interpretive dancers or historians? Critical race theorists? What does all this say about our values?
The plumber is in the physicist's apartment, knee deep in crap, fixing the toilet. Suppose the plumber has interests, things she would do if she didn't have to wade through crap all the time. Suppose she's actually a fairly talented artist. Why does the physicist get a "free ride", intellectual freedom and financial security, while the plumber deals with the crap?
Of course in our society you _do_ get a "free ride" by owning enough stuff. That's a separate, but related conversation.