I think you need to readjust your attitude.
BookBub is an advertising service. You're not lucky to receive a deal. You are the one paying BookBub. A BookBub deal may have been a career maker in 2015, but it is not today. It will likely net you a lot of sales or downloads, but it may or may not make you money. No one can tell you that. Random authors in random genres certainly can't tell you that.
If you want a better answer, look at the deals in your genre, and find books similar to yours. How much do they sell? What is the sellthrough? Would they earn out?
What sort of sellthrough do you normally have? Do you have opportunities to make money on this deal? It is much harder to make a profit on a free sale on a standalone than a free sale on book 1 of 8.
IIRC, all of my BookBub deals have earned out. Back in the day, some made thousands. These days, it is pretty common I earn 1-2k on the first free BookBub deal in any given series. That is looking at the increase in sales over the next 30-60 days versus the previous 30-60 days. It is possible other factors increased those sales, but I attribute all to BookBub.
For the next free run (on that book or another), I typically earn about half that, if I rerun the deal on the same book or run the deal within the next 6-12 months. I often earn 1-2k if it has been 18+ months since my last free sale and I'm running a different book. It does depend on the length of the series and the average sellthrough within it though. And it also depends on how much BookBub readers like the book. The books that do best on BookBub are not necessarily the books that have sold the best overall or books that are most popular with my fans.
Occasionally, with a free run, on a popular book, in a long series, I earn 3-4k or more. But that is rarer these days.
For a .99 sale, I typically earn under 1k, so my net is likely a few hundred dollars.
(These are all books in KU).
I apply for BookBubs regularly and I get them regularly, but there are some books with BookBub simply does not want to promote, for one reason or another. I have books that get a BookBub every time and books that have never gotten a BookBub, and BookBub prefers certain sorts of covers and blurbs. They're readers are not necessarily aligned with FB, Instagram, or Amazon readers.
There is no such thing as a sure thing in publishing. You should always spend money ready to lose it. You will likely make money on a BookBub, but you might not.