It is not rigged. It is random. It is like gambling. The chance to get bb7 is less than 1% with gold keys. Silver keys are 10x less chance than gold keys. But, you do get similar values of experts and vet as you convert them to gold to get these items. What you have received is normal. For gold keys, about 80% are +10 experts and 20% +1 vet and sometimes +100 experts and premium/boost. For silver keys, the chance of getting vet is much higher than experts. 10 kpcoin = 1 gold key or 200 gold. Do the math. It costs about 2800 gold to get 2200 experts. That is around 1.3 gold per expert. 1 gold key (or 200 gold equivalent) gives 150 experts. That is around 1.3 gold per expert. You get about the same experts from gold keys as gold, except that it is random that you will get other things you do not want. But, you also have the chance to get bb7.
Yes, i heard someone who got bb7 with less than 100 gold keys. I also heard some who spent more than 200+ gold keys without getting a bb7. It is a gamble.