For a long time, Flutter could do no wrong. It made the incredibly shrewd acquisition of the US fantasy sports app FanDuel shortly after the legalisation of US sports betting in 2018. Then, just before the first lockdown created a nation of online poker players, it bought PokerStars. The poker boom of 2020 softened the blow, for Flutter, of the decline in live sports betting.  The stock went on a tear. Already quite a big company, it more than tripled in value in the year after March 2020.  Since then, Flutter has taken a turn. It has given back about…