Mostly because I tend to get sidetracked by other options - paralysis by analysis. As I mentioned in another thread, I think that I want to move from my GH-5 to the new GH-7. That will require a new housing, but I can keep my current ports and lenses. This makes the most sense, but I start looking at all the other options, and the cost and then get stuck.
I am lucky in that my partner actually doesn't mind what I spend on underwater video equipment, it is still cheaper than what I spend on sports cars and motorcycles...