The reasons to invest in Bitcoin Cash (BCH) were pretty straightforward. The coin had a faster transaction speed than Bitcoin ( BTC ) and was a lot cheaper to buy. A large number of investors believed it could outperform Bitcoin , especially those who missed the Bitcoin rally. Roger and his team also used aggressive tactics to attract more investors which was also made possible due to lack of competitive coins back then. So, people who thought the Bitcoin rally was overextended and it was too late to invest in Bitcoin , those people invested in Bitcoin Cash .
More on this analysis here: https://cryptodaily.co.uk/2018/04/bitcoin-cash-bch-starting-lose-charm/