They spent more than $15.5 million, according to the article
Though you are correct it is a durable asset. (As are buildings.)
A 'temporarily reusable' tier might be something like "DVD dot com" or "rtx dot com" or something -- presumably there's a lot less money in DVD than there was 20 years ago, and presumably raytracing won't be an exciting high-end thing people are excited about 20 years from now. They're valuable and quite reusable at one point, but could become low-value by the time the company decides to unload them.
Not that huge.
15M is like one month of salaries for 500 engineers, so like 40% of their whole eng. team