Ussher's proposed date of 4004 BC differed little from other Biblically based estimates, such as those of Jose ben Halafta(3761 BC), Bede (3952 BC), Ussher's near-contemporary Scaliger
(3949 BC), Johannes Kepler (3992 BC) or Sir Isaac Newton (c. 4000 BC).
Keppler was disfellowshipped for his bible checking, Newton kept mum about some of his bible research to avoid that fate, which was often fatal.
P.S. A Wt speaker put the limit to 2075, giving us 15 more years than the genius.