$300 an hour is about 600k/year. In many cases, this is actually probably a good estimate for developer opportunity cost for the company.

My working career is only a couple years old at this point so I'm more junior but in both of those years I can point to contributions that were worth more than 600k to the company. That being said, I personally don't even make a third of that $300/hour. But that's the whole reason a company decides to hire you -- they think you'll make them more money than you'll cost.

What's the "5" in your equation? :)

However it's still way too much. 300 * 8 * 22 * 12 = 0.63M per year. In my opinion you must be at least Linus Torvalds's deputy to pretend on that.

Did she mean daily rate? I wonder if a junior ask for this rate, of course the company has no chance to afford a senior dev.