Just look at the volatility. Bitcoin is insanely volatile. That's not a sign of a stable investment. Gold is better, but not a lot, because like Bitcoin, it doesn't represent intrinsic economic value, it only represents people's trust in it, and that can change. Not as dramatically as Bitcoin, because gold is much more established, but in the end, it's still just a shiny metal.

ETF and land represent real production value. Land most directly of course, and that's about the most stable as you can get: even if literally the entire economy collapsed, at least you still have land you can farm.

ETFs are a bit indirect; to be more direct, you'd have to buy shares of the individual companies represented in them, but for most people that's a lot of work. ETFs get you the same thing. Their composition might change, but only slowly and tied to a whole bunch of criteria. And in the end, they do represent the economic value of real companies that produce things.