I don't know that high executive salaries are evidence of anything other than theres an executive class which exists, even in the non-profit world. You'll need to come up with better arguments that there's a homeless-industrial complex, which there very much is, but complaining that the leader of a 700-person organized doesn't deserve more than a low end FAANG shows a very naive understanding of how the world works. $313k is cheap for that kind of work. A CEO for a 700-person strong tech company makes well into a million dollars a year, counting equity. Complaining that executives make a lot of money at a non-profit is like complaining that things cost money in the first place. there is a need for someone to do job X. people who do job X cost $xxx/hr. it doesn't matter the context of that job, whether it's running a business, managing armed forces, saving the homeless, or writing a web browser, that's what that job pays.

A better argument for there being a homeless-industrial complex would to say there are incentives for organizations to expand operations rather than fix problems, and then give examples where organizations didn't fix problems because it would result in their lowered funding.