You might want to read thru the comments on this thread. A lot of good plausible outlooks as to why the price tag was justifiable. Playstation and Bungie also have a Q&A that could shed some light.

I wonder if the PS4 will still be included in these live service games? Typically, most live services aren’t the most graphically demanding with maybe a few exceptions. And with nearly 120 million PS4’s out there and with the huge slowdown in PS5 shipments due to the shortages for who knows how much longer, I wonder if Sony will want to tap as much of last gen as they possibly can.

I can see Sony also releasing these games on PC and mobile maaaaaaybe on day 1. When it comes to games that are designed to run for years and years, PC and mobile are arguably the top 2.

Yes, these, and also:

Imagine Bungie is a bunch of former American nuclear physicists who've been missing, but just popped up in Iran, and their location has leaked. Iran of course (as well as others), are just itching to have some nukes of their own.

If you're Sony (America) in this case, it doesn't matter how many nukes you already have, it's better for you to get your hands on those physicists before someone else does and uses them for their own means, potentially to the detriment of yours.

It's not always about, what can you do for us? Sometimes it's about, how could you be used against us or anyone else?

MS supposedly used Bungie in the wrong way. Activision supposedly used Bungie in the wrong way. Sony is in a way playing the hero, saving the good guy from eventually becoming part of another villains plan.

Bear in mind, this story is just getting started. Hero's aren't perfect and sometimes make mistakes. Will the hero succeed, or become the villain?