You will have a blank tech tree but keep all your completed missions. You can now re-spend your points.
So in short: "Reset tech tree" exists only in Survival Mode’s pre-game setup, giving you flexibility to experiment with different strategies without penalty.
Note: As of the latest game updates (v1.1+), the save files are partially encrypted. Some players report needing a third-party "Save Editor" tool (available on GitHub and Nexus Mods) to do this correctly.
Why? Because the game is designed around . The developers want you to finish a run, win or lose, and then start a brand new game with a different strategy. However, this design choice leads to significant confusion, especially for new players who invest points into "Economy" only to realize they can't build advanced military units.