Huh, was about to ask when it was halved, before taking a look at the date and seeing it was last year. Of course Bitcoin is always taking the lead and will continue to take the lead. No altcoin can compete with Bitcoin, despite it has been forked many times, BCH and Bitcoin Gold, but it still kept moving ahead of all of them. The other two halves were just failure, though BCH is still trying in the market, but the current fork on BCH has made things worst. And people even believe that it was also one of the reason for the market going down.
Bitcoin can easily regain dominance in future because we had sharp falls in the value of the coin years ago and the loss was recovered so this time again the loss in the value will recover. Just stay hopeful and think positively.
This time around it wasnt halved or something, this is just a normal fall in the market. And Bitcoin is still dominant as it has the biggest market cap and also stands as the number one coin with the highest price too. None of these altcoins can compete with it. Even Bitcoin alone can be a good investment, there is no need for diversification.