I get those referral offers all the time, too. I just looked at the last one I received a week ago and it is only for 30,000 points. The offer before that which recently expired was for 50,000 points. So, the 50,000 offer may be expired. It comes and goes.
BTW, I believe it is against the rules here on Disboards to solicit others for referrals to get bonus point or other compensation.