Bitcoin is not guaranteed to be profitable.
If you do not use leverage then you are guaranteed that the most that you could lose is 100% of what you invested. It is misleading to proclaim that bitcoin is guaranteed to make profits.
Many folks invest into bitcoin aggressively because they believe that the odds are pretty high that it is going to have a higher value (price) in the future as compared today and even accounting for the debasement of the dollar. There are also a lot of upside scenarios that make bitcoin amongst the best (if not the best) of asymmetric bets the upside, but even if bitcoin is amongst the best, it still is not guaranteed to be profitable in the future as you are proclaiming.
If you think deeper, you are right JJG, that Bitcoin also does not guarantee 100% profit. Because we don't know what will happen in the future, and sometimes many people make mistakes that result in losses for themselves. That's why we are taught to use cold hard cash when investing in bitcoin. If you think more deeply, this is a sign that Bitcoin also has risks, although not as big as other crypto assets. That's why we have to use cold money when investing in bitcoin. Apart from that, let alone Bitcoin, no other assets in this world actually guarantee 100% profit. Because it's called investment, sometimes you can make a profit and sometimes you can make a loss. For this reason, if Bitcoin is considered to guarantee 100% profit, perhaps this assumption is also not correct. Because after all, bitcoin is an investment asset which certainly has the same imperfections as other assets. But the difference is that bitcoin is very decentralized, perhaps this is the difference between bitcoin and other assets. Because the decentralized system makes investors more confident in continuing to invest in the long term. For this reason, I can conclude that bitcoin does not guarantee profits, but bitcoin at least has risks that are not too big for investors.