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.
Well you are correct but am probably sure that making 50% of profits in the next 10 years is kind of 40% guaranteed.
However, some folks invest aggressively in bitcoin as you said because they are 100% profit minded investors. But I still doubt that they can invest for long term mostly when they observes that they aren't making any profits at the moment they might sell at a lower price.
Actually, profits is not guaranteed on Bitcoin investment that's why one need to invest with what they can afford to lose (from their leverage).
I believe that an experienced Bitcoin investor knows the risks on bitcoin investment as Bitcoin might dip at any moment so they will not invest aggressively on it.
Some reasons why investor tend to invest in Bitcoin during the dip is probably because when it goes up they will make profits even though it's little, but those are short term investors.