Stats are very clear. Bitcoin dominance is at historic highs and this means that the altcoins are not doing good. Against fiat currency, there has been some improvement, but their exchange rates against Bitcoin is down by a lot. In a matter of just 3 months, Bitcoin market share has increased by 10%, and the altcoin share has gone down by the same amount. 2021 is going to be even worse for the alts.
This high dominance of bitcoin is due to the XRP dump, which lost about 70% of its value. Now only the price of BTC remains stable due to the fact that money received from the sale of altcoins is invested in it. In my opinion, the dominance of BTC can decrease to 64%, which will lead to an increase in the price of altcoins.