Why were people prone to invest in risky schemes in the 20s?

If we're talking about the 1920's people were prone to invest in risky schemes as the 20's had been a time with booming economic gain in America. Also there was a ban on alcohol and some other drugs so it was common for people to do risky schemes such as buying drugs (tobacco) or going into secretive places that Make moonshine which is a type of alcohol

Not sure, google it.