Don't you think it'll be a wrong investments decision to sell your Bitcoin just before the halving happens, usually during Bitcoin halving, the price of Bitcoin use to pump therefore it'll be a wrong decision to sell Bitcoin for altcoins right now. You can do that after Bitcoin has gotten a new all time high that's very high to give you big profit. But still I won't sell all my Bitcoin to invest into altcoins as altcoin are more risky and very unpredictable than Bitcoin.
The best time to make profits from altcoins is after Bitcoin halving is over as many Bitcoin investors will begin to start selling their Bitcoin to invest in altcoins and you have to wait to confirm the narratives that money will be flowing into as not all altcoins will be receiving the money that's flowing out of Bitcoin to altcoins. Monitor whales wallets to see what altcoins they're investing into and follow them.