Nobody really knows if this is a bubble or not. The problem is the large number of investors who placed their money in this market without knowing anything about cryptocurrencies and who were carried away by advertising and the promises of getting rich overnight. Of course, without these investors, the cryptocurrencies would not have had that huge growth.
But before investing again you have to wait for that feeling of fear to disappear, as fear can blow up a market very quickly. As experts say, a market can fall much faster than it rises because of the fear of losing everything.