Because we live in a capitalist system in which everyone who is not a studio mogul has to scrimp and save to eat, yes, McLain shouldn't have to beg on the street to stay fed and clothed. But then again the rest of us should not, and as I am incapable of earning money (in that I do a thing and someone compensates me for it) the capitalist system we live in would have me starve or succumb to the elements while I try to sleep on hostile architecture.
And while I don't expect any concern for my personal welfare, it does mean my (economic) demand for a GlaDOS Digital Assistant comes to an early and tragic end, as does the demand for many other things, since the only way to earn money is by obligations to work for rich people. (And they hate most of us.)
So, while the system we have might allow for McLain to live, I won't get to enjoy her work, or really anything, because it's all about giving our resources to those who already hold the majority of them.
Once we have social systems that allow us all to have comfortable lives, McLain might be happy doing the work for the good of the community, and for the glory of fame, and not to be richer than the rest of us.
During the COVID-19 Lockdown of 2020, a lot of people were furloughed and didn't get paychecks rather had to live on social benefits, many of whom took up hobbies that they really liked and could find a way to monetize, leading to the great resignation of 2021, which is one of the reasons we're taking unions seriously right now, so I know that some people will do art for art's sake when they don't have to spend all their time slaving to someone else for their next meal.