People who are wise and have good experience in investing will not only invest in one type of investment, they will try to divide it into several types, real estate, stocks, gold, and also Bitcoin, because only investing in Bitcoin is too risky, even if you always believe that the four-year cycle will always occur and will provide big profits for those who own Bitcoin at low prices, but unexpected things can happen such as the latest ATH not being as high as expected. One of my investments besides Bitcoin is stock, and even then not in just one company, there are several to avoid risk.
Bitcoin has good fundamentals at the moment but it must be remembered that Bitcoin's scale is still too small and price changes often make investors quite uncomfortable, especially for those who are inexperienced.
I am not one of those smart people, I do not like to invest into those other stuff because to me they are not really good investments. I am not against diversification, I am more than willing to invest into other things as well, the only problem is that I do not find anything that is worthy to my investment.
This doesn't include real estate, that I do not invest into because I do not have that kind of money, there aren't many places you could invest with just a little money. These days the most important options are either gold or stock if you want to diversify from bitcoin, and those two do not look good to me. If there was a better option, I would definitely put some of my money there instead of all into bitcoin.
You don't find anything worthy of your investment other than Bitcoin? I'm afraid you're living in the past. The financial ecosystem is an ever-changing, dynamic landscape that requires constant adaptation. You say you're not smart? There are DeFi protocols, Synthetic Assets, and even Bonded Tokens that offer yields unheard of in traditional markets!
Don't write off stocks and gold just because they don't "look good" to you. What are your metrics for that assessment? Market cap? Liquidity? Have you factored in the impending advancements like ESG metrics and robo-advisors shaping the stock markets?
Your logic about not having enough money for real estate is puzzling. Ever heard of Real Estate Investment Trusts (REITs)? Minimum investments are often as low as $500. The days of needing a fortune to diversify are long gone