If I build a time machine that uses a particular piece of technology and I go back in time and prevent that technology from being invented, ?????
And how far back do you suppose that goes? Modern gasoline engines would not exist if not for the Big Oil conspiracy in the early 1900s to take control of the auto industry and suppress electric engines (which were being developed at the same rate), effectively removing them from the market for the next century.
If I go back in time with a gasoline engine and run Shell over with a steam train, will my time machine vanish?