I'm going to explain this in the simplest way possible, while expressing the implications this place might have on you.
You think to yourself, these reviews on Glassdoor can't be all accurate, right? Here's the thing. You take a job like this, you could possibly have a different experience than the majority of the people on here leaving horrible reviews about the CEO and the company. Anything is possible. The Million Dollar Question is, are you willing to risk wasting your time and hurting your career by working here, especially with so many warning signs?
Oh, and where to begin with the CEO. The negative feedback about the CEO is absolutely true, except for when people say that he doesn't know what he's doing. He does know what he's doing when it comes to the product. What he doesn't know in the SLIGHTEST bit is how to communicate with people, to lead people, to speak in a way that doesn't come off condescending. HERE'S THE HUGE RED FLAG: Before being hired, I asked the interviewers about the company culture, and they all told me, "well, you should probably read the glassdoor reviews." Why would they tell you to read the reviews, knowing how bad they are? Think about that.
Again, it's possible that this won't be your experience. There are a few people who haven't had negative experiences and who actually like the CEO.