How do you actually explain Bitcoin to someone who thinks their savings account is totally fine?

My sister in law keeps telling me her high yield savings account is all she needs and that bitcoin is just gambling. She is not dumb at all, she is actually pretty sharp with money, but every time I try to bring up why I have been stacking since 2017 the conversation dies fast. I get why it sounds sketchy from the outside. The volatility alone is enough to make anyone nope out of the conversation before it even starts.

The thing is I do not want to come across like I am recruiting her into something or hyping her up with price targets. That never works and honestly feels gross. But I also genuinely think having even a small position matters long term and I want her to get there on her own terms.

Has anyone had a real breakthrough moment explaining bitcoin to a skeptical but financially literate person? Not someone clueless, but someone who has read enough to have formed an opinion against it. What actually landed for them? Was it the fixed supply thing, was it the banking angle, was it just watching price long enough? Or does it just never work until someone is ready on their own and you are wasting your breath trying?