How Do Ultra-Wealthy Individuals and Institutions Actually Buy and Store Bitcoin?

I’m relatively new to Bitcoin and the crypto space, and I’ve been wondering how things work at the highest levels of wealth.

For most retail investors, buying Bitcoin is straightforward: we use an exchange (like Bybit, Binance, Coinbase, etc.) or buy through a P2P transaction. That’s how I got started.

But then I regularly see news headlines about billionaires, hedge funds, corporations, family offices, or other wealthy investors buying hundreds of millions (or even billions) of dollars worth of Bitcoin.

My assumption is that they don't simply log into Binance and place a market order like the rest of us. So how does this actually work?

• How do ultra-wealthy individuals buy large amounts of Bitcoin?
• Do they use exchanges, OTC desks, private brokers, banks, or specialized companies?
• Once they acquire Bitcoin, who actually holds the keys?
• Do they use commercial hardware wallets, or are there more sophisticated custody solutions?
• How do institutions handle security, inheritance, governance, and key management?

This also makes me wonder about the famous Bitcoin principle: "Not your keys, not your coins."

For regular users, the advice is usually to self-custody. But does that principle break down for billionaires, corporations, ETFs, and large institutions?

Do most of them actually control their own keys, or do they ultimately rely on professional custodians? If so, how does the Bitcoin community view that trade-off?

I’d love to hear from people who understand institutional Bitcoin custody and large-scale acquisitions.