This is also the best time to look for new projects to invest, as when bitcoin hits a new ATH it will be already too late for huge altcoins gains..
It's really difficult to decide to all-in on ALTS. Before the halving, BTC created a new ATH but it wasn't a really good time to invest in ALTS because the price of many has returned to retest the bottom in the recent market panic. I think DCA would be a more suitable investment strategy, especially for investors who are not good at technical analysis.
Personally I think buying altcoins with fiat currency is just daft and is usually a newbie mistake to make. When Bitcoin is outperforming the dollar, then you shouldn't be sitting in fiat (that covers 2023 basically). As for it being "too late" to buy altcoins when Bitcoin reaches new ATH, it is in fact exactly at this time that altcoins usually reach their lowest value against Bitcoin, or otherwise at the same time. So while many noobs are waiting to buy some sort of "break out" to higher prices for altcoins with fiat, after losing 60% fiat value in BTC terms, I'm instead (still) waiting to buy the dip using Bitcoin. I'm averaged in a bit, but with most altcoins still making new lows against BTC, there is certinaly no hurry here, it'll probably take another Bitcoin ATH in order for them to finally bottom out imo.
It's always been the strategy to buy Bitcoin at it's lows, then using a trading account of BTC to invest in altcoins at their Bitcoin lows, often a year or so later and only after Bitcoin prices rise to new ATH. Otherwise using fiat currency you will usually lose 50-70% on investment already in Bitcoin value that is, so you will always be chasing 2-3x to make up that loss first. Fundamentally, if your altcoins isn't outperforming Bitcoin, there is no additional value in holding it. Diversification for diversification sake is otherwise meaningless imo, as Bitcoin remains the no.1 crypto and outperforms altcoins 80% of the time (time wise, even if not price wise). Even if there are some alts that I hodl because they have maintained their BTC value for example.