Name of the game to stack BTC??

Hi all,

Relatively new to the crypto space, and ive read on multiple occasions the aim should be to stack BTC over alt coins. My Q and appreciate this may be contentious is; alt coins % return tends to be higher than BTC so what am i missing? Both seem pretty volatile..

I currently have approx. £15k in alt coins, and approx. £8k in BTC, should i planning to sell alts post alt rally and buy more BTC once we head into bear market? Or buy more alt coins in the bear..