He made a small fortune on warrants. He can hold the common for years. Even if the company goes bankrupt he will still have made a small fortune from the sale of the warrants. Based on his posts he is holding common shares and waiting like us all.
It is an idiom. OK. I googled 'laughing all the way to the bank' and it showed 'make a great deal of money very easily'. Bigger is already way ahead and he will be further enriched. I am not going to go into the Woodford saga.