Just show them how much profit you made form bitcoin.
If they see that they will immidiately join and understand what bitcoin.
yup this make sense , show them the historical data of bitcoin from it's humble beginning up to it's current value today , every year bitcoin was undeniably increasing in value , show them how much they can profit in less than 6 months if they can see that the return is good they might think again on investing on bitcoin.
Not only profits but you should also show them how you are earning bitcoins and how your are getting paid on regular basis by showing them your bitcoin wallet as if they don't have to invest money and if they are getting paid by only working on it then they will be easily convinced to start earning bitcoins as not all have money to buy bitcoins but if they come to know that they have opportunity to earn it then it won't take much time for them to get into bitcoins.