also i would love to choose bitcoin but if i have large amount of fund, i didn’t invest full amount in bitcoin, i will invest some gold because it’s 100% safe assets, and then i will invest in bitcoin it could be long term or short term, if in online security is a big issues, it’s not easy to protect online currencies, so without good security knowledge you can loss your money.
I see the issue of security as a minor and should not be seen as a reason for not investing in bitcoin or other online currencies since there's no maximum security guarantee nowhere.
It is good to always diversify your investment but when comparing between these two (bitcoin and gold), the former seems to be advantageous over the latter. Bitcoin is open to all irrespective of where you are so long as you have access to network and wallet but gold is easily accessible for everyone to invest. Mind you, no asset is 100% safe for investment, there's risk no matter how small it is. Remember, the higher the risk, the bigger the profit but you need to play smart.
Your statement about always diversifying is not correct. Diversification can serve as a way to preserve your wealth, yet anyone in their earliest stages of investing will likely start from one investment at a time, and so if someone is new to investing, it makes no sense for them to get into a bunch of things at once. Accordingly, there is no reason not to just start out with both bitcoin and cash, and figure out the proportions. The cash serves as back up funds of various sorts and perhaps as a means to offset some of bitcoin's inevitable volatility. We know getting into bitcoin it is inevitably going to be volatile and we are not 100% assured that the BTC price is going to go up, yet if we spend time accumulating it then once the bitcoin holdings get to a certain size, then we might consider diversifying, whether that is after it gets to 1-2 years of expenses or some other size, we can determine when we would like to spread out our investment beyond just bitcoin and cash.. including a consideration that it could take 5-10 years or longer just to build up an investment to be the size of something like 1-2 years of expenses, partly depending on how much is regularly invested (such as using DCA) and also if the investment might appreciate in value during the time of investing.. and no guarantees on that either... but there is no need to buy gold for the mere sake of it or for the mere sake of diversifying.. except if you cannot resist investing in gold, at least keep it to a somewhat small portion of the size of your bitcoin holdings..perhaps 5% or less... but yeah, people can decide what they like, but there is no requirement or even supposed smartness in diversifying, especially for folks in their first several years of investing.. and the point at which diversification becomes more important as a consideration comes moreso from the growth of the investments that will also help to inform whether and/or how much to diversify into other asset categories, which would traditionally be thought of as equities (stocks), bonds, properties, commodities, cash/cash equivalents.