It’s not entirely true. Bitcoin price is volatile so you can have profit as quickly as 1 day or shorter if you manage to purchase Bitcoin right before the price rally started.
It’s not necessarily true that you will only have profit on Bitcoin when holding long term while in fact Bitcoin price pump happened in spread time frame which means you can gain profit regardless how long or short you hold.
The price of Bitcoin is above $100,000 today. So what you mean is that the price of Bitcoin has not increased. Basically, the point is that we should never look at the price of Bitcoin and should always continue to buy. If you think that the price of Bitcoin has increased a lot, then you can never invest, so it is never right to look at the price of Bitcoin.
There is no guarantee that you will make a profit if you invest in Bitcoin. There are many risks in Bitcoin investment, but long-term investment is much less risky than short-term investment. If you can hold your saved Bitcoin for a long time, then you can make a profit.