Destiny brings in hundreds of millions of dollars a year without having to make annual releases, it's not a bad investment it's just long term. I do wonder if there was a bidding war of some kind going on behind the scenes that got the price up to what it is though, it's hard to believe that was what either side thought Bungie was really worth unless Sony just really wanted them. Personally, I haven't played Destiny 2 since about 3 weeks after launch but I'm just not much of an online gamer so this doesn't do anything for me one way or the other either.
It seems like people want everything to be about console wars though, spend a huge amount of money on a company just to take their games away from other players which dramatically decreases the value of the company you just spent billions on, virtually ensuring you'll never make that money back. There is no one company that can be purchased that will take the majority of players from one platform to the other, the vast majority of PS4 owners didn't buy a COD game, most xbox one players didn't buy Destiny 2 etc.