How can we erase the negative thoughts of people over bitcoin? Nobody has any negative thoughts over dollars or there various currencies, We need to think about it.
You can show them the benefits of using bitcoin. Like you said, a fiat transaction will take 2-3 days to arrive, so you tell them a bitcoin transaction will be completed faster. You can also tell people to not fear volatility. As soon as they receive bitcoin they can convert it to fiat or another stable crypto currency, if they aren't confortable with the risk.
People fear what they don't understand. So explain the basics and if possible, guide them through their first bitcoin transaction to make their experience best as possible. You know, first impressions are lasting.