Somtimes its helpful to explain to them that the only thing that makes fiat money "valuable" is the simple fact that we as a society ascribe value to it. I.e. we get money for the sake of spending it on other things. Other than that fiat paper money isn't worth the paper it's printed on.

It doesn't always work as people are stubborn as fuck. But it can be helpful to lay this point at their feet and let them decide if Botcoin has any real value. Atleast you tried. Then when they come crying to you at 150k you can be like I told you to buy bitcoin you ignored me