What I have seen here is two factors that lead to masayoshi son lose in bitcoin, first he followed the advice of a bitcoin market booster which is very wrong because in a volatile market such as bitcoin there is no professional analyst that can give 100% prediction on the future of bitcoin market and secondly haven invested in middle of 2017 when the price was heading to the sky he should have hold his bitcoin when is has gone down and already running at lost. Because you only lose when you sale below cost price so in his best interest he should have considered hodling till the market recover before selling.
Are you joking? I even believing they have their own strategist on crypto yet you said they following some uncertain resources? Anyway, we never know what he is thinking about losing this number, may be he can recover or may be get some big profit on others markets or shares which is cost him losing this much is pretty normal thing. If you think they deliberately losing this money on bitcoin without having desire to getting it back then the SoftBank name will mean nothing