Item Boxes are gamble. Buy them to start gambling. Well though my unluckiest gold box is where i got only level 18s torso, 2 modules, level 22s legs, and a sector eye.

Buy enough boxes and you'll see it all. I've gotten gold boxes with nothing but 5 kits in the past. I've also gotten gold boxes with 3 mythicals.

There is about a 1/25 chance of buying 4 boxes and getting 0 mythicals. Certainly it sucks but it's not all that unlikely either. In buying 4 boxes you would expect to get 3 mythicals and on average you will. However, in small samples sizes anything can happen.

If you are only interested in mythicals I highly recommend buying the new mythical box. There is no guarantee that you'll get the item you want but you will get a mythical 100% of the time at about the same cost as getting it from a gold box. On average a mythical from a gold box will cost about the same number of tokens as a mythical box costs. However, you get more items from gold boxes and if there are any legendary items you also want you may be better off buying gold boxes and taking your chances.