Why we need to wait for Bitcoin halving to buy altcoins?
You misunderstand if you assume the prices of altcoins will be lower during/after the halving. You must know that most altcoins follow the trend of Bitcoin price. When the price of Bitcoin increases significantly during/after the halving, the prices of altcoins will increase significant as well. In this matter, surely it is better to buy altcoins now, the prices are lower now. If you wait for halving, you probably will buy altcoins with more expensive prices.

Actually, the best time to buy altcoins and Bitcoin were during the first year of bearish season. Since the peak of bullrun season was in 2021, the best time for entry was in 2022. At that time, the prices of most crypto coins dropped very significantly. Even, there were altcoins that dropped the prices more than 90%. But since many FUDs at that time, many people feel worried to buy and missed the chance to buy at the cheapest prices.