I think the answer is simply that private money is cheaper than public money for these companies right now.

OpenAI hasn’t had any problems getting impressive amounts of funding. So why ipo?

Two reasons. First, there's more money in the public markets, and Altman's appetite seems insatiable (he's the one who's been calling for gigantic, government-sponsored "Manhattan Project" efforts related to AI); and second, public money comes with fewer strings attached - private investors want protections, board seats, etc.

	▲	mbreese an hour ago \| parent \| next [-]
		I certainly wouldn’t say that public money comes with fewer strings attached. Just different strings. But the strings that come with public money tend to have sharper legal teeth behind them.
	▲	sgt101 an hour ago \| parent \| prev [-]
		I don't think this is right. Who knows what Altman wants? It's moot what individual motivations are as he is definitely fronting for investors who have significant power in the business. Public money comes with legal fiduciary duties. The reason to IPO is to get private money out, materialise the whole valuation.