There is no solid thing can bring passive income certainly to you. Stocks, gold, real estate, Bitcoin, altcoins, they are all risky and only different in short term and long term. With your different expectation on ROI, passive income from your investment, you will choose different assets for profit.

The asset can be stocks, gold if you like traditional market, but if you want to join emerged markets like Bitcoin and cryptocurrency market, it's good if  you pick Bitcoin, and say no to altcoins. Thinking of passive income by buying altcoins and staking with high APY is very risky. Big lesson like Terra and some DeFi platforms in a last bear market are unforgettable with me. I am against idea of staking to have passive income.