The biggest obstacle I've run into with fairly smart fiat apologist type people with Bitcoin is they just don't believe it's possible dispite it working today.
They laugh when you say Bitcoin can move ten million dollars of value for 70 cents in a cash final way. They say things like "who's running the infrastructure" and are concerned that Bitcoin could just disappear tomorrow.
They're not willing to do the work to understand why Bitcoin has a fixed supply.
HFSP I guess.