Therapist Pay?

I need to hear from therapists in private practice. I'm graduating in a few weeks and the numbers just aren't adding up. So, my friend wants me to work for him. He wants me to start billing 100/hr immediately and he said he'll do a generous split (around 70/30) to help me get started. So with these numbers, I'm not understanding why the reports on glassdoor and all those are so low? Am I missing something? Because it seems like I should be making very good money, but any research will tell you that in private practice, you'll make 50 or 60 a year.....but where is all that money going???? Even with much lower percentages, it still looks like you should be making way more than this, so either I'm completely missing something or those numbers are wrong? Please help!