They actually didn't care about their money, what they want to tell to the community is that all can be easily manipulated if you have a huge amount of money. Yes, money is almost everything especially in crypto world as it can easily dictate the price of a certain coin/token if they like it to hype using their huge money by buying almost all the selling order in any exchange.

Spending that huge amount of btc in exchange of 5 million doge bet is kinda crazy but I am sure that there is a twist behind this action though I cannot really point out what it is, what I am sure is that there are other reasons why they pulled this kind of unnecessary actions.