a. they dont know where to spend it.. thus think its not a currency because they seen no real world usage of it
b. they are informed of bitcoin(by idiots) as a 'get rich quick' scheme. thus they dont see it as a viable currency because they are only informed about getting rich.. so think its a scam
c. they are not informed about what differences different coins offer and why bitcoins value underlying the market is higher then others. so they think bitcoin is just speculatively pumped by 25000x above a coin offered for $1.. so they dont trust bitcoin and think it can crash to $1
..
so, the solution
dont explain bitcoin like a greedy wallstreet salesmen talking about it like a get rich scheme
instead show local retailers nearby that accept it/prove its usefulness
explain how some altcoins only cost <$35 of electric combined to get a newly generated coin. and bitcoin cost $15k+ a coin. and so the markets speculate from that point and above
some speculate by 1x-6x above value cost. some speculate by 45x
more speculations means less value is protected. thus stay away from those extreme high speculations
explain how some coins have deflationary supply and some dont. and how that alters the value/cost fundamentals too