Buy bitcoin because it is what you can spend, it is an asset, it has limited supply and it is decentralized compared to altcoins, altcoins are not decentralized.
Every time is the right time to buy more Bitcoin most especially when you are buying for long-term purposes.
Not everytime is the time to buy bitcoin, bitcoin will still rise to $100000 but those that buy when it was in $60000 or above will not be happen right now, the best time to buy bitcoin is in the bear time when many people will not afraid to buy.