A Satoshi Millionaire is someone who owns at least 0.01 BTC or 1 million satoshis. 1 Bitcoin equals 100 million satoshis (aka sats) and people refer to satoshis when talking about Bitcoin in smaller amounts.

There are tons of people encouraging others to focus on becoming a satoshi millionaire because there will be a day in the future when 1 US dollar equals 1 satoshi.