Predominantly I buy index funds, and hold a lot of cash.
I have no idea which direction any market is moving in, I simply buy assets which I believe have a lot more potential to move in one direction than the other. Oil may go to $1/barrel, but it won’t go to 0. And, in a few years, it may go to $100. I can accept risk and loss, but what I can’t accept is a high cost just to hold something, or the risk that comes with not really understanding an investment.
Interest rates can go negative, sure, but I think it’s much more likely that German 10 year bonds go to 5%, at some point, than negative 5%. Same with Japan.
I don’t mind being wrong, but I want my investments to move directly with the asset price in a predictable, transparent way. My investment horizon is a few years. These are my primary existing investing ideas: long natural gas/long oil/short bonds. That’s it. At some point both interest rates and energy prices will rise, and I’m happy to wait.