Warning: lengthy philosophical post ahead! 
Portfolios aside, this is one of the fundamental questions of human beings, has always been and will always be.
We live in a world that doesn’t explain itself. As Kierkegaard said: ”life can only be understood backwards, but it must be lived forwards”.
How we deal with this uncertainty is a very personal matter. Depending on the times that we live in, we’ll be influenced by one scary scenario or the other. For example, my parents grew up during the cold war and for them, an escalation to a World War 3 was a very real threat. On the other hand, if we read a book like “1913” by Florian Illies, we see that almost nobody had any clue that World War 1 was about to destroy their lives; they all had their own worries and were caught by surprise. Us nowadays, we think about the impact of AI, social inequality, government debt, hyperinflation, etc. Or maybe China is indeed going to be a problem, as this article in Foreign Affairs suggests (English, not paywalled)?
Interestingly, I think that many people don’t think about these things at all and just presume that nothing will ever change. Unsurprisingly, the topic comes up regularly in this forum: people who have the analytical skills to bother about their finances will end up seriously thinking about the future. Which is of course a good thing.
Yuval Noah Harari writes in “21 Lessons for the 21st Century” that driven by technology and AI (quote) “not just entire classes, but entire countries and continents might become irrelevant.”
There’s also an interesting interview with the historian Edward Chancellor in NZZ (German, not paywalled), where he expects increasing social unrests.
I believe they are both right.
Scay prospect; however, I do not believe that we’re going towards a total collapse of law and order (at least in developed countries). Unrests, crises: yes; apocalyptic collapse: no. Of course, there are people who say otherwise, but they don’t know any better than I do. If it really comes to a total collapse however, then Bitcoin will be as worthless as gold. You won’t be able to walk to your local farmer and exchange that gold nugget for corn. You’ll be ambushed ten times over before you get there. As @Wolverine says, we’ll need friends and skills; but hopefully not guns and ammo, I might add. At least I’m not expecting and preparing for that.
My investment strategy is thus: I agree with @dom.swiss that rather than bonds, money is currently the better option. I would consider short-term government bonds for the risk-free part of my portfolio, but as long as they have a negative yield, I’ll stick with cash.
I do not hold gold as I believe that it works based on the “greater fool principle”. Gold can only gain in value if there are other people who are more scared when they buy it than I would have been when I bought it. It is an unproductive good, it generates costs, it is not as negatively correlated to e.g. stocks as it should be, and its historic yield is rather low. And as I said above, I don’t expect a “Walking Dead” world where I’ll exchange it for food.
I also do not hold Bitcoin for the reasons that I’ve written here in this forum: I consider it as digital gold, though its easy tradability gives it some characteristics of a currency; but I don’t concede it the capability to replace government issued currencies.
The risk-exposed part of my portfolio is in stocks. Not only because of the historic and expected returns, but also because by investing in companies, I invest in people: there are billions of people out there who go to work every day, companies that compete with each other, technologies that are evolving and new products that hit the market.
Or to say it differently: I have trust in my government (cash, bonds) and in humanity’s potential to innovate and grow (stocks). I balance these two in a way that I’m comfortable in bearish and bullish times. Been doing it since 2006 and went through the 2008 crisis and I’m fine this way.
That would be the old and infamous market timing trick… 