Definately that bulb holding the betta is too small. I think it's lack of knowledge on what's a resonable size to keep bettas in.
If you think about it was it the ecospheres that came of first with the 4" small globe which has 3-4 opae? When I first saw those I thought they were the coolest thing. As I started to gain more knowledge it turned in WTF that's really messed up.
I myself have jars with opaes in them. The smallest being a quart. This is the smallest I would go. Everyone in there seems to be fine.