BRKB- should I diversify and look better alternatives?

I own BRKB in a retirment account at 10% of total account value and about 14% in a brokerage account. I bought these long time ago and they have appreciated well. Looking at BRKBs performance and post Buffett scenario, Is it wise to diversify (reduce to half or less of my current position) and buy QQQM and SPLG ? what do you all think?