To me, it's Bitcoin backed financial and insurance products, and likely loans, financing options, and so on. Just because Bitcoin has a fixed supply, doesn't mean you can't make money from other people with your own Bitcoin. It could be in the form of liquidity moves, ie: someone needs some quick Bitcoin to cover a trade or whatever, boom, Strategy has you covered. He said never sell, he didn't say anything about never monetize or loan it.

here is a graphic to understand yield 🍌➡🎅➡💩💩