I think anyone who has worked for a good mix of startups and corporations will understand the extreme difference. And yes, being around a bunch of highly optimistic people inside corporations is depressing.
And it's depressing that people get paid more to do useless bureaucratic things while in a corporation than adding real value whilst in a startup.
I blame Federal reserve banks and fiat money for this. That's why I work in cryptocurrency space now. Cryptocurrency allows you to get profit from systemic inefficiencies just like corporations but you get that nice efficiency, value-creation feeling of a startup.