Do you really put what you saved on a board & cpu away for 2 to 3 years for your next build ?I'd say X470 board ~£170, with a 3700X ~£320, would give you 97-99% of the 9900K, but with budget left over for a new board and CPU after 2-3 years, and being way ahead of where you'd have been otherwise.
Surely by the time 2 or 3 years has gone past your buying interest would be something else.