yes, right when the market improves, the profit from trading increases because all altcoins rise together but if the market is bad the altcoin rises on the market slightly
that's not automaticly happen in market.price moved very dinamic based on supply and demand on tokens or coins.so opinion that tell if bitcoin rise than altcoin down and vice versa was not totally true.
There's a time especially when strong bull lifted the market, both alts and bitcoin is rallying up together, it's depends on how investors will follow
every coins to invest their money, the value will grow when there's more willing investors to hold than to sell the coins.