Interested in other ways of avoiding going to zero?

I think it's useful to make a clear distinction between two principal types of large risk.
(1) The risk that the PRICE of your asset drops a whole lot, but not the value.
(2) The risk that the VALUE of your asset drops a whole lot, and generally the price along with it. Permanent loss of capital.

Arguably type (1) can simply be ignored...just wait it out. And by extension type (2) is the only true risk in any type of investing.

Phrased that way, the best way to avoid the risk is to avoid buying anything whose true intrinsic value has a meaningful chance of a meaningful and lasting drop. That's hard, but not impossible. Beyond deep understanding of your investments, there is diversification. It's not magic, but it can help. If you put 1% of your money into each of 100 companies with different characteristics, it's probably less likely to go to zero than if you put 100% into one company. It might have a higher chance of an uninteresting return, but a lower chance of a spectacularly bad one.

That's all a bit of an oversimplification. Other types of risks you might consider:

There is a type (1.5) risk between the two above: the intrinsic value didn't take a meaningful and lasting hit, but you bought at too high a price so when the price drops you will have taken a lasting loss. Maybe not permanent, but lasting enough that it really hurts, like the people who bought Microsoft at end 1999 and were underwater for 15 years despite the firm doing well throughout. This is avoided by not overpaying for things, even very good things. I recommend never assuming you can sell at a multiple of future earnings higher than the teens...that simple rule cuts out quite a lot of exuberance temptations, but still allows for investments in very high growth opportunities which may have no current earnings.

There is downside deviation risk: the risk that the real total after-tax return on your portfolio falls short of what you truly require. e.g., if you are a pension fund that has to pay out a certain amount in future to beneficiaries, and that payout requires you to make a real 6%/year, then achieving a real return of 4% or 5%/year is a very real failure risk. At a personal level, the "avoid a diet of dog food" risk.

There are also way-out-on-the-tail risks, but most of them can not be hedged against using financial instruments. Asteroid hits, nuclear wars, permanent closure of markets, expropriation without compensation, and so forth. Some people would argue for a small bar of gold in the sock drawer as the best way to hedge this, but I'm an optimist.

Jim