Ask anyone where they keep their savings, and the answer is almost always the same: a fixed deposit, a mutual fund, some gold, a government bond, or whatever their version of safe is. They understand that ETH or an index could return more, but losing money they already have hurts more than missing a gain they never had. That asymmetry is why the largest pools of capital sit in things that promise the principal back. It would be a mistake to read that as wanting no risk at all. These are the same people who watch every rally they sat out and feel it. What they actually want is a specific shape: keep their money safe and capture some of the upside if the market runs. Traditional finance has sold exactly this shape for forty years under the name "capital protection," one of the largest corners of the structured-product world, with hundreds of billions in buffered funds and protected notes. The classic construction has two ingredients. You take most of the money and buy a zero-coupon bond worth less than par today that matures at your full principal. Whatever is left, the discount, you spend on call options. If the market rises, the calls pay and you share the gain, if it falls, the calls expire worthless, but the bond matures at par and your principal is whole. The bond is the floor, the options are the upside, and banks have packaged the two together for decades. The trouble is that the option leg is not always available or affordable. Options cost the most when volatility is high, exactly when people want protection most, and for some assets an option long enough to match your horizon barely trades. There is a second way to build the same shape without touching an option. It is called constant proportion portfolio insurance, or CPPI, developed by Perold in 1986 and formalized by Black and Perold in 1992. The strategy is a single rule: define a floor, the value you refuse to fall below, measure the cushion above it, then hold a multiple of the cushion in the risky asset and park the rest in something safe. When prices rise, the cushion grows so you hold more risk. When prices fall, the cushion shrinks so you sell risk and move to safety. Near the floor you are almost entirely safe. A strategy that sells into weakness and buys into strength produces a convex, option-like payoff without anyone selling you an option, your own rebalancing creates the protection. The multiplier determines how aggressively you lean into risk and the largest sudden drop you can survive, one divided by the multiplier. A conservative multiplier holds less risk and survives bigger gaps, an aggressive one holds more and survives less. Picking it means choosing how much downside protection you buy and how much upside you forgo. But selling low and buying high in choppy markets causes bleed when prices go sideways. De-risking near the bottom can mean missing part of a sharp recovery. Its main weakness is gap risk: if prices jump instead of moving smoothly, the portfolio can breach the floor before rebalancing. The multiplier must be sized for how violently the asset can move. Most people already try to make this trade by splitting savings between something safe and a little risk. They run a crude manual version of the rule, rebalanced by mood. CPPI simply writes the rule down and follows it precisely, turning the cliff people fear into a glide down to a floor they chose themselves.