Like I imagine tons of people will be hitting them up for pet projects of varying quality after this announcement.
Though looking at Wikipedia, they have been around since 1984, with many high profile donors, so maybe they are institutionally able to deal with huge variations in budget?
https://en.wikipedia.org/wiki/SETI_Institute
My (uninformed) guess is that $200 M must to be the biggest gift by an order of magnitude, or maybe 2.
Or are these kind of estate gifts split up over multiple years, with strings attached? Either that or you just get one huge check :)