There is no guarantee that you will make a profit by investing in Bitcoin. The Bitcoin market is very volatile, there is never a guarantee that you will make a 100% profit by investing in Bitcoin. But the risk in long-term investment is much lower than in short-term investment. No one is ever able to predict, all we can do is guess.
I disagree with you if you said that all we do is to guess. If you talk about guessing that means you're indirectly telling us that bitcoin investment is just like that of gambling that we guess correctly most times, while sometimes your guessing may not also work as you expected. Bitcoin is a highly volatile asset no doubt, it may not be suitable for everyone's risk tolerance. Many investors believe that Bitcoin has the potential to appreciate over the long term, making it a good investment for those who are willing to take the risk.
Well he is correct but not for long term investors. Guessing the price movement is done by short term traders, those who thinks they're buying at the dip and wait for the market to pump a little within a short period of time and sell when it goes up. Short term traders loss from the market because they are guessing the price should go up within a limited amount of time. If I'm being honest, I've never seen any long term trader who actually complains bitterly about lossing from his investment this is because from technical analysis it shows that the overall movement of bitcoin is bullish irrespective of the small bear seasons that we experienced and aside that, the concept of demand and supply explains that the higher the demand and limited amount of supply creating scarcity, the product price will eventually go up. So you see that there are no guesses around here, but short term traders who happen to trade around those bearish season are likely to run at loss because of the volatility and markets manipulations.