You are not entitled.
No matter how hard you work or how good you think your work is, you are not entitled to representation or a publishing contract. This is a business, not a sponge-bath for your ego. If an agent doesn’t think they can sell your work, or a publisher doesn’t think they can make money on it, they will reject it. Accept that.
You are certainly not allowed to assault a literary agent because your work is rejected, and if you have any sympathy with the man assaulting her you are a shitty human being and you can unfollow me right fucking now.
Cross-posted on my other blogs to boost signal.
I fucking LOVE books 
Absofuckinglutely.