It was never going to pay off by 2042
That number was based on the original $3 billion giveway, not the newer $4.3 billion - and it really is a GIVEAWAY - there are no corporate taxes on manufacturing in Wisconsin, so they are actually writing checks to Foxconn! Trump and Walker were taken for a ride by the Chinese like no one ever has before!
The other problem is that it is located only 20 miles from Illinois, so some percentage of the workers will be Illinois residents who won't even pay taxes to the state of Wisconsin!
This is a giant boondoggle, it isn't surprising though that Trump is still crowing about it because he doesn't know or care about any of this. Or know or care what the truth is about much of anything since his followers get their news from mostly fact-free sources like Drudge and Fox.