The three things that concern me about Bitcoin are the following:

1. The problem of scalability, it is necessary to evaluate the effectiveness of exchanges for millions of daily transactions, especially in the case that a practical and massive use is achieved.

2. Security from the point of view of hash control by Chinese mining, although it is very unlikely, there is a small possibility that somehow the security will be altered.

3. A potential fall of Bitcoin because another Altcoin had a very strong impact on the ecosystem and attracted the attention of millions of people, displacing Bitcoin and relegating it to a low position.