The youtuber probably thinks that btc will peaked when altcoin season is happening.
Me personally will still hold my bitcoin. I always taking into account the fragmentation of liquidity on altcoin and the fact that big chunk of BTC inflow is coming from ETF where they don't have the chance to rotate to altcoin besides ETH.

If you truly want to get on the altcoin season you need to be wise in choosing which altcoin to invest.
However if your target of holding BTC is for long term, these altcoin season things are just meaningless noise.