SpaceX (NASDAQ:SPCX) just completed one of the biggest IPOs in history.

Millions of investors wanted in.

Most didn't get what they asked for — and now they're left wondering how to play the space economy without the stock that started the conversation.

But here's the thing: some of the biggest gains from a landmark IPO don't come from the company that went public.

They come from the companies that benefit after it does — the suppliers, competitors, and infrastructure plays that suddenly find themselves in the spotlight.