I saw some claims that the wallet the coins were in had millions. There are some wallet analyzers that can be accurate, but tend to be uncertain. The problem is that wallet could be hosted with someone else and only a certain address was allocated to Putt. The "wallet" had extremely high transaction rates. Many daily. I don't have any reason to think Putt is sitting on over 150BTC. It's possible, just seems unlikely with that particular wallet.