It says that the price of many coins increased in 2017 during the famous bitcoin boost, but it is less likely to happen again because today investors are preferring new altcoins which real value and concept.
Clearly new altcoins with real value are the perfect ones to put money in. But those coins are really rare and that's not a wise strategy. People just don't want to commit their old mistakes in the past. That's why they're cautious and keep their money on bitcoin rather than altcoins. This also explains why investors are preferring new altcoins than old altcoins.