What’s the end game for bitcoin?

So I’m thinking about taking some profits from the sale of a property and buying the fidelity FBTC etf. I like the fact that they own their own bitcoin and aren’t using a third party. I also don’t want to take the chance of self storing it and losing my key or getting hacked. The plan is to buy a bunch of shares and to let it sit in the fund for at least 15 years. I keep seeing everyone saying never sell bitcoin, even 20 years from now. So my question is how would you capitalize on your investment to pay for retirement, or a house, if you never sell any bitcoin? I would think you would take some lifestyle chips off the table and maybe occasionally sell enough to buy a car or a house at some point. Is the right game plan to always hold it and maybe take loans out against your asset to buy the things you need to live?