It is unclear how he developed an interest in cryptocurrency but he wrote in his manifesto that his profits from investing in the cryptocurrency Bitconnect enabled him to travel.
https://thenextweb.com/hardfork/2018/01/17/bitconnect-bitcoin-scam-cryptocurrency/
obviously a ponzi, so ponzis work for the first investors, who started bitconnect and how did Brenton Tarrant make his money there. Who gave hime the lead?