Cool, well done! Nice to see that I'm not the only crazy one here.
When did you start?
I started much later than you, but because I wager like crazy (the most on any site but that is because most of it also done in 2016) I get almost maximum free btc. I am basically now only 2 tiers away from the max free bonus and that is because I have been claiming a bit more than usual since winning the lottery;)
Good luck! And it's amazing where you got so many referrals! Care to share how you advertise?