BTC has not peaked by any means. Its rise has been mild so far and it should go near $100K at least. Alts outperforming BTC is a great sign for the best phase of the crypto bull market.
At present many of them I know are more interested in altcoins and looking to accumulate as much a possible. Some getting converted their btc to altcoins, might be just want to catch the trained as seems to be season and altcoins rising very quickly so making some quick profits and may convert back again to btc later on.