The same way you get people to use a website / app ... just use it yourself in front of them and they will passively convert.
I've noticed, some people that I tried too hard to convince to use steem and talk about how it works, the rewards, the blockchain, they confuse everything and think it's a scam or something weird... If you look like a casual user to them, and you keep using it, it will peak their interest and they will ask about it.
Reverse psychology ;)
well my friends don't belive me when I say that with the money from my introduction post I bought myself a carpet. They think it's a scam. They just need some more time :)