Bogleheads aren't wrong, historically. At least, not in the general sense that buying index funds and mostly forgetting about it is smarter than trying to beat the market with individual stock picks and timing the market.

But, that philosophy came about in an era when there were protections for small investors that prevented the richest man on earth from dipping into your retirement fund to make himself even richer. I don't know how to be a smart investor when the game is so thoroughly rigged for a handful of billionaires.

I'm informed enough to see what they're doing and why, but I'm not informed enough to know how to prevent them from wrecking the economy for normal folks while enriching themselves. I don't think information alone can solve the problem for the majority of people. Retirement accounts aren't often easy to change, non-retirement accounts have tax consequences, timing the market as a normal retail investor is risky.

I don't really have advice. If I were directly holding an index that tracks the Nasdaq 100, I would get out of it, and take the tax hit. But, I suspect the impact and risk will cascade outward. Nvidia has exploded in price based on actual revenue (though I suspect it will be temporary, and have to come back to earth in time). SpaceX is entirely fantasy land. It doesn't have revenue to justify anything like the price they're launching the IPO, and when indexes are forced to buy it, everyone holding those indexes provides exit liquidity for the same scammers who've been hyping it.

If you are subject to capital gains taxes, this would likely be a bad idea? (Though I have no clue how American 401k work in this regard.)

isn't this also "timing the market"? which most people agree is a bad idea

Wouldn't it make more sense to move it after the IPO? The supposed scam here is that Elon et al will dump their shares and crash the value, but that cannot happen for 90(?) days after IPO. So I think you should let your index buy the inflated IPO, then sell it before the crash, not sit it out entirely.

You are giving up equity premium for the time till everything settles. You will also not know when that is. It's going to be more like a long term ticking bomb that may take years to detonate.